# "Too much violence, not enough humanity."

June 30, 2011 9:01 AM Subscribe

Giles Turnbull responds to the "20 craziest job interview questions" (as asked by such companies as Pottery Barn and Google).

*VWR International: How would you market a telescope in 1750 when no one knows about orbits, moons, etc.?*

VWR International doesn't know a lot about the history of astronomy, I guess.

posted by kenko at 9:12 AM on June 30, 2011 [47 favorites]

*Suppose you had eight identical balls. One of them is slightly heavier and you are given a balance scale. What’s the fewest number of times you have to use the scale to find the heavier ball?*

Easy. Put four balls on each side, remove one from each side at a time until the balance levels out.

posted by dunkadunc at 9:12 AM on June 30, 2011 [4 favorites]

Holy shit, dunkadunc, that's genius.

posted by kenko at 9:13 AM on June 30, 2011 [2 favorites]

posted by kenko at 9:13 AM on June 30, 2011 [2 favorites]

*What did you play with as a child?*

Myself.

*maintain constant, unblinking eye contact, do not smile*

posted by quin at 9:13 AM on June 30, 2011 [17 favorites]

*VWR International: How would you market a telescope in 1750 when no one knows about orbits, moons etc.*

1750? Galileo had been dead for 100 years by then, dumbfucks.

posted by Jehan at 9:14 AM on June 30, 2011 [9 favorites]

*Suppose you had eight identical balls. One of them is slightly heavier and you are given a balance scale. What’s the fewest number of times you have to use the scale to find the heavier ball?*

Easy. Put four balls on each side, remove one from each side at a time until the balance levels out.

Easy. Put four balls on each side, remove one from each side at a time until the balance levels out.

Or put all eight on the scale then remove them one at a time, noting the drop in weight for each.

posted by Shepherd at 9:14 AM on June 30, 2011 [2 favorites]

Sorry, should have been less sweary, but I googled what VWR International actually do.

posted by Jehan at 9:15 AM on June 30, 2011

posted by Jehan at 9:15 AM on June 30, 2011

*Twenty-five racehorses, no stopwatch, five tracks. Figure out the top three fastest horses in the fewest number of races.*

1 race, 1 track, 25 horses, top 3 finishers are the three fastest horses. I expect a check for $1 million promptly.

posted by nathancaswell at 9:15 AM on June 30, 2011 [3 favorites]

The answer to every single one of these questions is, "That depends on what you think you'll learn about me from my answer." And then, also, "Fuck you, this interview is over." Possibly followed by a Stone Cold Stunner.

posted by uncleozzy at 9:15 AM on June 30, 2011 [41 favorites]

posted by uncleozzy at 9:15 AM on June 30, 2011 [41 favorites]

*1 race, 1 track, 25 horses, top 3 finishers are the three fastest horses*

The question has been misreported: you can only race five horses at a time. (At least in the version I heard.)

posted by kenko at 9:16 AM on June 30, 2011

I would just stare back nervously and say, "I like turtles."

posted by punkfloyd at 9:18 AM on June 30, 2011 [9 favorites]

posted by punkfloyd at 9:18 AM on June 30, 2011 [9 favorites]

*Twenty-five racehorses, no stopwatch, five tracks. Figure out the top three fastest horses in the fewest number of races.*

The question has been misreported: you can only race five horses at a time. (At least in the version I heard.)

The question has been misreported: you can only race five horses at a time. (At least in the version I heard.)

That one's kind of stumped me: you can run five races of five horses, and then a final race with the fastest from each, but that doesn't guarantee that the fastest three horses weren't #1, 2 and 3 in your very first race, or whatever.

posted by Shepherd at 9:18 AM on June 30, 2011

punkfloyd:

Alright, you're great ... zombie.

posted by filthy light thief at 9:20 AM on June 30, 2011 [2 favorites]

*I would just stare back nervously and say, "I like turtles."*Alright, you're great ... zombie.

posted by filthy light thief at 9:20 AM on June 30, 2011 [2 favorites]

*Sell me an invisible pen.*

It will give you a flat stomach, rock hard erections, and the respect of your children.

posted by The Whelk at 9:20 AM on June 30, 2011 [12 favorites]

The correct answer to all of these questions is "I've made a huge mistake."

posted by 2bucksplus at 9:21 AM on June 30, 2011 [40 favorites]

posted by 2bucksplus at 9:21 AM on June 30, 2011 [40 favorites]

Next year's hot interview question: "how would you market a history book to dumbfuck VWR International execs who can't even manage to read wikipedia?"

posted by phunniemee at 9:21 AM on June 30, 2011 [6 favorites]

posted by phunniemee at 9:21 AM on June 30, 2011 [6 favorites]

"

How do you know which of the 2 balls you just took off is the heavier ball?

It seems like the easiest solution is to divide them in 2 groups. The heavier of the two groups is kept and then divided in 2, repeat and then you choose the heavier of the two remaining balls. So three steps

posted by vuron at 9:21 AM on June 30, 2011 [12 favorites]

*Easy. Put four balls on each side, remove one from each side at a time until the balance levels out.*"How do you know which of the 2 balls you just took off is the heavier ball?

It seems like the easiest solution is to divide them in 2 groups. The heavier of the two groups is kept and then divided in 2, repeat and then you choose the heavier of the two remaining balls. So three steps

posted by vuron at 9:21 AM on June 30, 2011 [12 favorites]

*Jane Street Capital: What is the smallest number divisible by 225 that consists of all 1’s and 0’s?*

Fucking Haskell fuckers.

posted by enn at 9:21 AM on June 30, 2011 [6 favorites]

*I would just stare back nervously and say, "I like turtles."*

Was that for this interview?

Holden: You're in a desert, walking along in the sand, when all of a sudden you look down...posted by ennui.bz at 9:22 AM on June 30, 2011 [16 favorites]

Leon: What one?

Holden: What?

Leon: What desert?

Holden: It doesn't make any difference what desert, it's completely hypothetical.

Leon: But, how come I'd be there?

Holden: Maybe you're fed up. Maybe you want to be by yourself. Who knows? You look down and see a tortoise, Leon. It's crawling toward you...

Leon: Tortoise? What's that?

Holden: [irritated by Leon's interruptions] You know what a turtle is?

Leon: Of course!

Holden: Same thing.

Leon: I've never seen a turtle... But I understand what you mean.

Holden: You reach down and you flip the tortoise over on its back, Leon.

Leon: Do you make up these questions, Mr. Holden? Or do they write 'em down for you?

Holden: The tortoise lays on its back, its belly baking in the hot sun, beating its legs trying to turn itself over, but it can't. Not without your help. But you're not helping.

Leon: [angry at the suggestion] What do you mean, I'm not helping?

Holden: I mean: you're not helping! Why is that, Leon?

[Leon has become visibly shaken]

Holden: They're just questions, Leon. In answer to your query, they're written down for me. It's a test, designed to~~provoke an emotional response~~determine whether you are an optimal job candidate... Shall we continue?

From personal experience, I'd just like to add a 21st.

Amy's Ice Cream: Decorate this paper bag.

posted by spamguy at 9:22 AM on June 30, 2011 [7 favorites]

Amy's Ice Cream: Decorate this paper bag.

posted by spamguy at 9:22 AM on June 30, 2011 [7 favorites]

Yeah. I've never taken a CS class in my life, but I think based on that Facebook question I just rediscovered the concept of sorting algorithms from scratch. No guarantees that it's a

I wish I interviewed with the kinds of places that asked questions like these. Because I just fully crushed about 15 of these questions, I think.

posted by penduluum at 9:22 AM on June 30, 2011

*good*sorting algorithm, mind you.I wish I interviewed with the kinds of places that asked questions like these. Because I just fully crushed about 15 of these questions, I think.

posted by penduluum at 9:22 AM on June 30, 2011

Several years ago I contemplated taking a part-time job at Target. They have computers for would-be applicants set up in the lobby of the store. To complete an application, you type in your basic information, and then you're given a series of statements, which you rate on a scale from "Strongly Disagree" to "Strongly Agree."

I was getting along just fine until I got to "Most politicians are honest."

I kind of figured they probably wanted me to agree with this statement, but the fact that they were looking for a sheepy, trusting sort of mentality in their employees gave me the creeps, and I left the store right then.

posted by duvatney at 9:22 AM on June 30, 2011 [2 favorites]

I was getting along just fine until I got to "Most politicians are honest."

I kind of figured they probably wanted me to agree with this statement, but the fact that they were looking for a sheepy, trusting sort of mentality in their employees gave me the creeps, and I left the store right then.

posted by duvatney at 9:22 AM on June 30, 2011 [2 favorites]

*Easy. Put four balls on each side, remove one from each side at a time until the balance levels out.*

And how do you know that...up to 5 weighings is the minimum? (Hint: You don't, because it isn't.)

posted by DU at 9:23 AM on June 30, 2011

*How do you know which of the 2 balls you just took off is the heavier ball?*

You know scales?

posted by Wolfdog at 9:23 AM on June 30, 2011 [2 favorites]

*How do you know which of the 2 balls you just took off is the heavier ball?*

You don't, so you have to use the scale twice. Still beats the canonical solution.

posted by kenko at 9:23 AM on June 30, 2011

*And how do you know that...up to 5 weighings is the minimum?*

The way I interpreted duncadunk, having four balls on each side, then just taking one off each side, is still only "one use of the scale".

posted by kenko at 9:25 AM on June 30, 2011

Could someone who knows more about guns than I do (that would be almost anyone) explain the Russian Roulette question? Because it seems like the obvious answer is not to spin the chamber...?

posted by tuesdayschild at 9:25 AM on June 30, 2011

posted by tuesdayschild at 9:25 AM on June 30, 2011

The Teenage Whelk is on the phone answering a automated interview to work the night shift at CVS. You have to press 1 for yes and two for no. The question is asked:

"Is Stealing Wrong?"

I stare at the phone. Stare at my application. Put the phone down and walk away.

posted by The Whelk at 9:26 AM on June 30, 2011 [1 favorite]

"Is Stealing Wrong?"

I stare at the phone. Stare at my application. Put the phone down and walk away.

posted by The Whelk at 9:26 AM on June 30, 2011 [1 favorite]

"

The problem is that each time you are taking off 2 balls that's a new measurement so you might be lucky and get it 2 steps but you could be unlucky and it might take more.

posted by vuron at 9:26 AM on June 30, 2011

*You don't, so you have to use the scale twice. Still beats the canonical solution.*"The problem is that each time you are taking off 2 balls that's a new measurement so you might be lucky and get it 2 steps but you could be unlucky and it might take more.

posted by vuron at 9:26 AM on June 30, 2011

You spin, because that still gives you a random chance of 5 empty chambers. In the already-been-fired gun, you know at least one empty chamber is no longer available to you.

posted by penduluum at 9:26 AM on June 30, 2011

posted by penduluum at 9:26 AM on June 30, 2011

**UBS:**If we were playing Russian roulette and had one bullet, I randomly spun the chamber and fired but nothing was fired. Would you rather fire the gun again or respin the chamber and then fire on your turn?"We do three bullets! One! Two! Three! Three bullets!"

posted by boo_radley at 9:26 AM on June 30, 2011 [3 favorites]

*Lubin Lawrence: If you could describe Hershey, Godiva and Dove chocolate as people, how would you describe them?*

A child, a divorcee, and a housewife who are about to get diabetes.

posted by The Whelk at 9:27 AM on June 30, 2011 [17 favorites]

*Suppose you had eight identical balls.*

Suppose I did, do you think I'd spend

*weighing*them?

posted by tommasz at 9:27 AM on June 30, 2011 [13 favorites]

If you spin the chamber again, you have a 1/6 chance of splat, and a 5/6 (about 83%) chance of no splat .

If you leave it where it is, you have a 1/5 chance of splat, and a 4/5 (80%) chance of no splat .

Depending on your goals in life, one of these strategies may be preferable.

posted by Wolfdog at 9:28 AM on June 30, 2011 [5 favorites]

If you leave it where it is, you have a 1/5 chance of splat, and a 4/5 (80%) chance of no splat .

Depending on your goals in life, one of these strategies may be preferable.

posted by Wolfdog at 9:28 AM on June 30, 2011 [5 favorites]

Thanks, penduluum.

posted by tuesdayschild at 9:28 AM on June 30, 2011

posted by tuesdayschild at 9:28 AM on June 30, 2011

*night shift at CVS. [...] "Is Stealing Wrong?"*

Everybody I knew in high school worked at CVS. The amount of merchandise they stole was astonishing. The case of Polaroid film was probably the best.

posted by uncleozzy at 9:28 AM on June 30, 2011

Oh, and wolfdog too.

posted by tuesdayschild at 9:29 AM on June 30, 2011

posted by tuesdayschild at 9:29 AM on June 30, 2011

*Or put all eight on the scale then remove them one at a time, noting the drop in weight for each.*

A balance scale only tells you if one side is heavier, lighter, or the same weight as the other.

posted by kmz at 9:29 AM on June 30, 2011

Oh man, I could have stolen stuff? Damn my curiously naive morality.

posted by The Whelk at 9:29 AM on June 30, 2011

posted by The Whelk at 9:29 AM on June 30, 2011

tuesdayschild: "

The answer is to spin the chamber. After the trigger is pulled on an n-shot revolver, you know that there are n-1 chambers remaining, any one of which could have a bullet. This gives you a 1/(n-1) change of blowing out your skull. If you re-spin the chamber, the odds go of shooting yourself in the head go back down to 1/n.

posted by mkb at 9:30 AM on June 30, 2011

*Could someone who knows more about guns than I do (that would be almost anyone) explain the Russian Roulette question? Because it seems like the obvious answer is not to spin the chamber...?*"The answer is to spin the chamber. After the trigger is pulled on an n-shot revolver, you know that there are n-1 chambers remaining, any one of which could have a bullet. This gives you a 1/(n-1) change of blowing out your skull. If you re-spin the chamber, the odds go of shooting yourself in the head go back down to 1/n.

posted by mkb at 9:30 AM on June 30, 2011

kmz: "

You are so close! Think it through.

posted by boo_radley at 9:30 AM on June 30, 2011

*A balance scale only tells you if one side is heavier, lighter, or the same weight as the other.*"You are so close! Think it through.

posted by boo_radley at 9:30 AM on June 30, 2011

In case you don't know scales, the heavy ball came off the side that's lower. That's how you can tell.

posted by Wolfdog at 9:30 AM on June 30, 2011 [1 favorite]

posted by Wolfdog at 9:30 AM on June 30, 2011 [1 favorite]

*Procter & Gamble: Sell me an invisible pen.*

I don't see the point.

posted by lucien_reeve at 9:31 AM on June 30, 2011 [67 favorites]

Actually the best interview question I had was at the Movie Material Store on 14th. Since it was all about film stills and posters and memorabilia, the entire questionnaire was "Where have you worked before?" "When can you work?" and then 2 pages of classic Hollywood trivia questions.

I've never felt so perfectly right for any job ever.

So of course they closed 3 months after hiring me.

posted by The Whelk at 9:32 AM on June 30, 2011 [2 favorites]

I've never felt so perfectly right for any job ever.

So of course they closed 3 months after hiring me.

posted by The Whelk at 9:32 AM on June 30, 2011 [2 favorites]

I think a lot of these old puzzles about scales are harder than they used to be, because Kids These Days

posted by madcaptenor at 9:32 AM on June 30, 2011

^{TM}have their fancy digital scales.posted by madcaptenor at 9:32 AM on June 30, 2011

*Suppose you had eight identical balls. One of them is slightly heavier and you are given a balance scale. What’s the fewest number of times you have to use the scale to find the heavier ball?*

It's a trick question. If you have 8 identical balls, none of them will be heavier.

posted by thsmchnekllsfascists at 9:34 AM on June 30, 2011 [39 favorites]

Worst case of that method is 4 weighings (4/4, 3/3, 2/2, 1/1), which may count as 1 "use" or which may count as 4 "uses" of the scale, depending on who's asking.dunkadunc:Easy. Put four balls on each side, remove one from each side at a time until the balance levels out.

If you instead weigh 4/4, then weigh the heavy-side balls (2/2), then weigh the heavy-side balls again (1/1), you'll always get the answer in exactly 3 weighings.

If you weigh 4/4, then take

*two*balls from each side, you get the answer in exactly 2 weighings every time. If the scales balance after removing two balls, you weigh the two heavy-side balls you removed; if scales don't balance, you weigh the two heavy-side balls left on the scale.

posted by Western Infidels at 9:34 AM on June 30, 2011 [12 favorites]

*Fucking Haskell fuckers.*

That's not a number.

I actually

*like*the Jane Street question. Here's a question in the same vein: 2

^{29}is a nine-digit number. All the digits are different. What's the missing digit? (So if 2

^{29}= 389167450 you'd answer "2", except it's not.)

posted by madcaptenor at 9:35 AM on June 30, 2011

Here is a twist on the Russian Roullette question

Imagine I put one... two... three! bullets in the chambers. Furthermore, these bullets are all adjacent to each other. So if you imagine I laid the chamber in a line, I have:

_ _ _ o o o (underscore represents emtpy, circle represents bullet).

Now, I take the gun, spin the chamber, place the barrel against my head, and pull the trigger.

Nothing happens.

Assuming you wish to live, is it better to spin the chamber again, or not?

posted by LoopyG at 9:35 AM on June 30, 2011 [2 favorites]

Imagine I put one... two... three! bullets in the chambers. Furthermore, these bullets are all adjacent to each other. So if you imagine I laid the chamber in a line, I have:

_ _ _ o o o (underscore represents emtpy, circle represents bullet).

Now, I take the gun, spin the chamber, place the barrel against my head, and pull the trigger.

Nothing happens.

Assuming you wish to live, is it better to spin the chamber again, or not?

posted by LoopyG at 9:35 AM on June 30, 2011 [2 favorites]

*Could someone who knows more about guns than I do (that would be almost anyone) explain the Russian Roulette question? Because it seems like the obvious answer is not to spin the chamber...?*

Pulling the trigger spins to the next chamber automatically. The only way to get access to the one chamber you know is empty is to spin.

posted by nathancaswell at 9:35 AM on June 30, 2011 [1 favorite]

*Suppose you had eight identical balls*

If they're identical, then they weigh the same.

posted by device55 at 9:35 AM on June 30, 2011 [2 favorites]

Oh wait, I got that wrong, that would still be 3 weighings.

posted by Western Infidels at 9:35 AM on June 30, 2011 [1 favorite]

posted by Western Infidels at 9:35 AM on June 30, 2011 [1 favorite]

*You are so close! Think it through.*

Huh? I was just pointing out that you can't "note the drop in weight".

posted by kmz at 9:35 AM on June 30, 2011

*I think a lot of these old puzzles about scales are harder than they used to be, because Kids These Days TM have their fancy digital scales.*

When I was a kid, I had a scale that dissolved after every 3 uses, so I had to be efficient when I weighed things.

posted by jeather at 9:35 AM on June 30, 2011 [2 favorites]

*Worst case of that method is 4 weighings (4/4, 3/3, 2/2, 1/1), which may count as 1 "use" or which may count as 4 "uses" of the scale, depending on who's asking.*

Always gotta define your terms, man.

posted by kenko at 9:36 AM on June 30, 2011

*Susquehanna International Group: Five guys, all of different ages, enter a bar and take a seat at a round table. What is the probability that they are seated in ascending order of age?*

I hesitantly put forth one in twelve as the odds.

For the first seat, any one of the five people can sit at it. At the second seat, any one of the four remaining, and so forth. This is 5x4x3x2x1, or 5!, which is 120 possible seatings. The ascending order depends on where you start (any one of five positions) and if you are going clockwise or counterclockwise, so there are ten sets of ascending orders of age.

Seems reasonable to me.

posted by adipocere at 9:37 AM on June 30, 2011

My favorite job interview questions started with "Are you now or have you ever been...?"

posted by oneswellfoop at 9:37 AM on June 30, 2011 [1 favorite]

posted by oneswellfoop at 9:37 AM on June 30, 2011 [1 favorite]

My daughter recently had to take an online application for some national chain store. It was a timed thing. As you got further into it, the questions became more and more bizarre, to the point where there didn't seem to be any sort of reason to the questions and no actual answer. And there didn't appear to be any actual end to the questions, even though it was timed. It really disturbed my daughter, as she started to feel like she was being set-up to fail.

posted by Thorzdad at 9:38 AM on June 30, 2011 [2 favorites]

posted by Thorzdad at 9:38 AM on June 30, 2011 [2 favorites]

LoopyG: nothing happened. So that means that you originally were shooting from chamber 1, 2, or 3 (numbering from the left). On the next shot you'll be shooting from chamber 2, 3, or 4. One of these has a bullet, two don't, so you have a 2/6 = 1/3 chance of dying. Which is better than 3/6 = 1/2 if you respin. But why are you playing this game, unless someone is pointing a gun at you saying they'll kill you if you don't play?

posted by madcaptenor at 9:38 AM on June 30, 2011

posted by madcaptenor at 9:38 AM on June 30, 2011

(There is actually a two-use solution to the eight balls problem, BTW. I remember that one from math camp.)

posted by kmz at 9:39 AM on June 30, 2011

posted by kmz at 9:39 AM on June 30, 2011

The scale answer is two:

(1) Break them into three groups - 2, 3, and 3.

(2) Set aside the group of 2, and weigh the three against three.

(3.1) Are they equal? If so great, then the heavier ball is in the group of two. Weigh those two against one another and the heavier one is apparent.

(3.2) Are they not equal? If not great, then the heavier ball is in the heavier group of three. Disregard the lighter group of three.

(4) Take the heavier group of three, set one aside, and weigh the remaining two. If those two are equal, the heavier one is the ball you set aside. If they are not equal, the heavier one is apparent.

(5) Ta-Da!

posted by AgentRocket at 9:39 AM on June 30, 2011 [86 favorites]

(1) Break them into three groups - 2, 3, and 3.

(2) Set aside the group of 2, and weigh the three against three.

*This is weigh number one*.(3.1) Are they equal? If so great, then the heavier ball is in the group of two. Weigh those two against one another and the heavier one is apparent.

*This is weigh number 2 (v1)*.(3.2) Are they not equal? If not great, then the heavier ball is in the heavier group of three. Disregard the lighter group of three.

(4) Take the heavier group of three, set one aside, and weigh the remaining two. If those two are equal, the heavier one is the ball you set aside. If they are not equal, the heavier one is apparent.

*This is weigh number 2 (v2)*.(5) Ta-Da!

posted by AgentRocket at 9:39 AM on June 30, 2011 [86 favorites]

How is the Russian Roulette one different from Monty Haul?

posted by foursentences at 9:39 AM on June 30, 2011

posted by foursentences at 9:39 AM on June 30, 2011

LoopyG: After you pulled the trigger, I am either sitting on one of two empty chambers or a bullet, so I have a 2/3 probability that I don't kill myself by just pulling the trigger immediately. If I spin the thing again, I have a 1/2 probability of landing on a bullet and killing myself.

Assuming you want to live, do not spin the chambers again.

posted by King Bee at 9:39 AM on June 30, 2011

Assuming you want to live, do not spin the chambers again.

posted by King Bee at 9:39 AM on June 30, 2011

*It really disturbed my daughter, as she started to feel like she was being set-up to fail.*

They're trying to acclimate her to the working conditions there.

posted by thsmchnekllsfascists at 9:40 AM on June 30, 2011

adipocere: I agree.

(Sanity check: for n people by this method you get (2n)/(n!) = 2/(n-1)!. If n = 3 you get 1. But of course if you sit three people at a round table then they're always in ascending order of age.)

posted by madcaptenor at 9:40 AM on June 30, 2011

(Sanity check: for n people by this method you get (2n)/(n!) = 2/(n-1)!. If n = 3 you get 1. But of course if you sit three people at a round table then they're always in ascending order of age.)

posted by madcaptenor at 9:40 AM on June 30, 2011

*VWR International doesn't know a lot about the history of astronomy, I guess.*

Maybe it's a trick question? You say, "Uh, people *did* know about those things in 1750" and you get the job?

posted by asnider at 9:40 AM on June 30, 2011

*Suppose you had eight identical balls.*

How would you put on your pants?

posted by louche mustachio at 9:41 AM on June 30, 2011 [2 favorites]

AgentRocket: Clever! I wonder how many people could figure that out in an interview situation.

posted by dabug at 9:41 AM on June 30, 2011

posted by dabug at 9:41 AM on June 30, 2011

*Fucking Haskell fuckers.*

Sorry, you don't get the job. The correct answer was Fucking

*OCaml*fuckers.

posted by qxntpqbbbqxl at 9:42 AM on June 30, 2011 [6 favorites]

*If you walk into a liquor store to count the unsold bottles, but the clerk is screaming at you to leave, what do you do?*

disable the phone lines, Double tap, chest and head, make it look like a robbery, count unsold bottles later at your leisure.

posted by The Whelk at 9:42 AM on June 30, 2011 [11 favorites]

**Shepherd**:

*That one's kind of stumped me: you can run five races of five horses, and then a final race with the fastest from each, but that doesn't guarantee that the fastest three horses weren't #1, 2 and 3 in your very first race, or whatever.*

__Solution__:

1. Run 5 races of 5 horses each. Note #1,2,3 finalists in each race.

2. Run #1 finishers from step 1 against each other. Note #1,2,3 finisher. Call these horses 2a, 2b, 2c, respectively. Horse 2a is the overall fastest horse.

3. Run a last race with:

- horse that came in 2nd against horse 2a during the first step
- horse that came in 3rd against horse 2a during the first step
- horse 2b
- horse that came in 2nd against horse 2b during the first step
- horse 2c

Total 7 races.

Actually got that question "cold" in an interview once, answered it, and got the job.

posted by ceribus peribus at 9:42 AM on June 30, 2011 [12 favorites]

LoopyG:

The answer is "don't spin".

Your diagram, numbered:

_ _ _ o o o

1 2 3 4 5 6

Cylinder "rotates" left to right, let's say.

If you just put the gun to your head, fired, and lived, you just pulled the trigger on chamber 4, 5, or 6. If it was chamber 4 or 5, your next trigger pull will be safe. If you landed on chamber 6, your next trigger pull will kill you. You did not land on chambers 1, 2, or 3, so those options are removed. You have a 2/3 chance of surviving your next trigger pull. If you spin the cylinder, your odds are 3/6 or 1/2. You've a better chance of living if you don't spin.

I now see that a lot of other people have answered already, but I am posting in spite of them.

posted by penduluum at 9:43 AM on June 30, 2011 [3 favorites]

The answer is "don't spin".

Your diagram, numbered:

_ _ _ o o o

1 2 3 4 5 6

Cylinder "rotates" left to right, let's say.

If you just put the gun to your head, fired, and lived, you just pulled the trigger on chamber 4, 5, or 6. If it was chamber 4 or 5, your next trigger pull will be safe. If you landed on chamber 6, your next trigger pull will kill you. You did not land on chambers 1, 2, or 3, so those options are removed. You have a 2/3 chance of surviving your next trigger pull. If you spin the cylinder, your odds are 3/6 or 1/2. You've a better chance of living if you don't spin.

I now see that a lot of other people have answered already, but I am posting in spite of them.

posted by penduluum at 9:43 AM on June 30, 2011 [3 favorites]

For the one about walking up steps, I can't make it mathy. The options are doing it in n steps, n/2 steps, and everything between n and n/2. How do you math that? Limits? y = lim(n/2 + 1 until n) ?

posted by Buckt at 9:43 AM on June 30, 2011

posted by Buckt at 9:43 AM on June 30, 2011

*It's a trick question. If you have 8 identical balls, none of them will be heavier.*

It is almost always the case, with this sort of gimmicky logic-puzzle question, that the tacit Step One in any successful answer is "figure out the question I really meant to ask and answer that instead of the one I actually asked." The hard thing is reading the interviewer's level of authoritarianism and figuring out if you should repair the question out loud in order to seem clever, or if it's better to shut up about it in order not to seem disobedient.

posted by RogerB at 9:43 AM on June 30, 2011 [10 favorites]

Also: I was acting like the "o" meant empty chamber and not full chamber, for some dumb reason.

posted by penduluum at 9:43 AM on June 30, 2011

posted by penduluum at 9:43 AM on June 30, 2011

*And there didn't appear to be any actual end to the questions, even though it was timed. It really disturbed my daughter, as she started to feel like she was being set-up to fail.*

That reminds me of the "IQ Test" that used to be on thespark back in the day (when they still had quizzes and stuff). It was basically a never-ending series of questions. The test would only end when you finally stopped clicking "next page". The faster you stopped, the higher your score would be.

Being a slightly obsessive trivia and puzzle player, I got a

*really*low score. Almost killed my roommate (who had linked me) that night.

posted by kmz at 9:44 AM on June 30, 2011 [3 favorites]

Nice answering on the Russian roulette variant folks!

Regarding the Google stair-climbing question. It's a question about the Fibonacci sequence. Keeping that in mind makes the answer come quickly.

posted by LoopyG at 9:45 AM on June 30, 2011

Regarding the Google stair-climbing question. It's a question about the Fibonacci sequence. Keeping that in mind makes the answer come quickly.

posted by LoopyG at 9:45 AM on June 30, 2011

*Oh wait, I got that wrong, that would still be 3 weighings.*

I got that one in three weighings, too.

4 balls on each side in the first weighing. Swap 2 balls on one side with 2 on the other and weigh again -- now we know which group of 2 balls weighs more. From there, you can just weigh the remaining 2 balls.

posted by The Great Big Mulp at 9:45 AM on June 30, 2011

*I actually like the Jane Street question.*

Is there some clever way to answer it that I'm missing? It seems like the only way to figure is to brute-force it:

CL-USER> (defun fucking-haskell-fuckers () (loop for i upfrom 225 by 225 when (every (lambda (char) (find char (list #\1 #\0))) (princ-to-string i)) return i)) FUCKING-HASKELL-FUCKERS CL-USER> (fucking-haskell-fuckers) 11111111100But I'm sure I'm missing something.

posted by enn at 9:45 AM on June 30, 2011

*It is almost always the case, with this sort of gimmicky logic-puzzle question, that the tacit Step One in any successful answer is "figure out the question I really meant to ask and answer that instead of the one I actually asked."*

But it's so glaringly obvious. It would be such a simple fix:

"You have 8 seemingly identical balls. One is slightly heavier..."

posted by thsmchnekllsfascists at 9:45 AM on June 30, 2011

A hint for the one about walking up steps: fucking like rabbits.

posted by madcaptenor at 9:45 AM on June 30, 2011

posted by madcaptenor at 9:45 AM on June 30, 2011

*If you walk into a liquor store to count the unsold bottles, but the clerk is screaming at you to leave, what do you do?*

What is the point of this question? It doesn't actually appear to be a logic puzzle, like most of them. Is it just: "How to you respond to pressure?" or what?

posted by asnider at 9:46 AM on June 30, 2011

*VWR International: How would you market a telescope in 1750 when no one knows about orbits, moons etc.*

1750? Galileo had been dead for 100 years by then, dumbfucks.

1750? Galileo had been dead for 100 years by then, dumbfucks.

Sometimes people teach you things other than what they mean to. Assuming that this is not a trick question, what we can learn here is the difference between a

*correct*answer and the

*right*answer.

posted by ricochet biscuit at 9:47 AM on June 30, 2011

Alright, I'll give the solution. A number is divisible by 225 if and only if it's divisible by both 9 and 25. For a number made up of 1s and 0s to be divisible by 25 it must end in 00. But for a number to be divisible by 9 it has to have its digits sum to a multiple of 9. So the smallest number made of 1s and 0s which is divisible by 225 is nine 1s followed by two 0s.

Although I bet at some point they've gotten the answer 11100001.

posted by madcaptenor at 9:47 AM on June 30, 2011 [22 favorites]

Although I bet at some point they've gotten the answer 11100001.

posted by madcaptenor at 9:47 AM on June 30, 2011 [22 favorites]

For the staircase question, let S(n) denote the number of ways to ascend an n-step staircase. You either start with a single step or a double step. If you start with a single step, there are S(n-1) ways to finish ascending. If you start with a double step, there are S(n-2) ways to finish ascending. So,

S(n) = S(n-1) + S(n-2)

It's a Fibonacci sequence. S(1) = 1 and S(2) = 2, go from there.

posted by King Bee at 9:48 AM on June 30, 2011 [3 favorites]

S(n) = S(n-1) + S(n-2)

It's a Fibonacci sequence. S(1) = 1 and S(2) = 2, go from there.

posted by King Bee at 9:48 AM on June 30, 2011 [3 favorites]

enn: "

Well, 0 divided by 225 yields an integer, so perhaps zero is the trick answer.

posted by mkb at 9:48 AM on June 30, 2011 [3 favorites]

*"*

Is there some clever way to answer it that I'm missing? It seems like the only way to figure is to brute-force it:*I actually like the Jane Street question.*Is there some clever way to answer it that I'm missing? It seems like the only way to figure is to brute-force it:

CL-USER> (defun fucking-haskell-fuckers () (loop for i upfrom 225 by 225 when (every (lambda (char) (find char (list #\1 #\0))) (princ-to-string i)) return i)) FUCKING-HASKELL-FUCKERS CL-USER> (fucking-haskell-fuckers) 11111111100But I'm sure I'm missing something.

Well, 0 divided by 225 yields an integer, so perhaps zero is the trick answer.

posted by mkb at 9:48 AM on June 30, 2011 [3 favorites]

The actual answer to the Russian roulette question is to just look at the side of the revolver, you can see the back of the brass casing and know if the next pull of the trigger will be the last.

Sometimes practical pragmatism beats math.

posted by quin at 9:49 AM on June 30, 2011 [12 favorites]

Sometimes practical pragmatism beats math.

posted by quin at 9:49 AM on June 30, 2011 [12 favorites]

Nevermind -- just saw AgentRocket's solution.

posted by The Great Big Mulp at 9:50 AM on June 30, 2011

posted by The Great Big Mulp at 9:50 AM on June 30, 2011

I like that answer madcaptenor. I also thought of 0 as being the right answer. But your answer is sexier.

posted by LoopyG at 9:51 AM on June 30, 2011

posted by LoopyG at 9:51 AM on June 30, 2011

The ball/scale puzzle you can do in two, even with nine balls, like

Hard mode: 12 balls, one is a

posted by Who_Am_I at 9:51 AM on June 30, 2011

**AgentRocket**says.Hard mode: 12 balls, one is a

*different*weight (heavier or lighter). Par: 3 weighs.posted by Who_Am_I at 9:51 AM on June 30, 2011

Riffing off of some of them.

Sell me an invisible pen. I already have. It's there on your desk. Now pay me for it.

Twenty-five racehorses, no stopwatch, five tracks. Figure out the top three fastest horses in the fewest number of races. Shoot twenty-two horses. The three remaining will be the fastest.

What is your strategy at table tennis? Please, in my culture we only refer to it as ping-pong.

If you could describe Hershey, Godiva and Dove chocolate as people, how would you describe them? Hershey is like total yo-in-your-face snowboarder, plain or with almonds. Dove is a puffy old white lady. Godiva is a nekkid chick on a horse.

You are climbing a staircase. Each time you can either take one step or two. The staircase has n steps. In how many distinct ways can you climb the staircase? My first action would be to place an "o" after the "n." Then there would be no steps.

How many cocktail umbrellas are there in a given time in the United States? Percentage of cocktails in the rain * (Total cocktails minus rained-on cocktails)

Would you be okay hearing “no” from seven out of 10 customers. No. No. No. No. No. No. Maybe.

Suppose you had eight identical balls. One of them is slightly heavier and you are given a balance scale. What’s the fewest number of times you have to use the scale to find the heavier ball? Drop each on the end of the balance and see how much the scale wiggles.

Estimate how many planes are there in the sky. There is only one plane, the Greek ideal plane. The rest are imitations.

If I was a genie and could give you your dream job, what and where would it be? Genie derives from the Arabic word for demon. So I guess, executive demon.

What did you play with as a child? My dead aunt Helga.

How would you market a telescope in 1750 when no one knows about orbits, moons etc. You can see your neighbors bodices.

posted by dances_with_sneetches at 9:55 AM on June 30, 2011 [9 favorites]

Sell me an invisible pen. I already have. It's there on your desk. Now pay me for it.

Twenty-five racehorses, no stopwatch, five tracks. Figure out the top three fastest horses in the fewest number of races. Shoot twenty-two horses. The three remaining will be the fastest.

What is your strategy at table tennis? Please, in my culture we only refer to it as ping-pong.

If you could describe Hershey, Godiva and Dove chocolate as people, how would you describe them? Hershey is like total yo-in-your-face snowboarder, plain or with almonds. Dove is a puffy old white lady. Godiva is a nekkid chick on a horse.

You are climbing a staircase. Each time you can either take one step or two. The staircase has n steps. In how many distinct ways can you climb the staircase? My first action would be to place an "o" after the "n." Then there would be no steps.

How many cocktail umbrellas are there in a given time in the United States? Percentage of cocktails in the rain * (Total cocktails minus rained-on cocktails)

Would you be okay hearing “no” from seven out of 10 customers. No. No. No. No. No. No. Maybe.

Suppose you had eight identical balls. One of them is slightly heavier and you are given a balance scale. What’s the fewest number of times you have to use the scale to find the heavier ball? Drop each on the end of the balance and see how much the scale wiggles.

Estimate how many planes are there in the sky. There is only one plane, the Greek ideal plane. The rest are imitations.

If I was a genie and could give you your dream job, what and where would it be? Genie derives from the Arabic word for demon. So I guess, executive demon.

What did you play with as a child? My dead aunt Helga.

How would you market a telescope in 1750 when no one knows about orbits, moons etc. You can see your neighbors bodices.

posted by dances_with_sneetches at 9:55 AM on June 30, 2011 [9 favorites]

Also, a faster brute-force method for the 0s and 1s problem: check 0, 1, 10, 11, 100, 101, ... to see if they're multiples of 225.

posted by madcaptenor at 9:55 AM on June 30, 2011

posted by madcaptenor at 9:55 AM on June 30, 2011

I still don't get the stairs. I don't see how it's a fibonacci sequence, either. I get your formula, but I don't see how it gives you the answer. Whatever step x you're standing on, it's just S(n-x) + all of the other ones. How does that eventually give an answer?

posted by Buckt at 9:55 AM on June 30, 2011

posted by Buckt at 9:55 AM on June 30, 2011

*Is there some clever way to answer it that I'm missing? It seems like the only way to figure is to brute-force it:*

225 = 5 * 5 * 3 * 3 or 25 * 9.

All numbers containing only 0's and 1's and divisible by 25 must end in 00.

All numbers divisible by 9 must have digits which sum to 9.

Smallest answer: 11111111100.

posted by nzero at 9:56 AM on June 30, 2011 [2 favorites]

*So the smallest number made of 1s and 0s which is divisible by 225 is nine 1s followed by two 0s.*

Wouldn't that be "one nine, one zero, eight nines, one zero"?

Personally I would have answered "225--as expressed in binary."

posted by stevis23 at 9:57 AM on June 30, 2011 [1 favorite]

You weigh two groups of three balls against each other. If they're even, then you weigh the other two balls against each other.

If one of the three groups of balls is heavier, then you pick two of those balls and weigh them against each other. Either one of them is heavier or the odd man out is the winner.

Two weighings, and no fucking about with removing and replacing individual balls one at a time, which appears less efficient to me.

posted by ten pounds of inedita at 9:58 AM on June 30, 2011

If one of the three groups of balls is heavier, then you pick two of those balls and weigh them against each other. Either one of them is heavier or the odd man out is the winner.

Two weighings, and no fucking about with removing and replacing individual balls one at a time, which appears less efficient to me.

posted by ten pounds of inedita at 9:58 AM on June 30, 2011

I got asked the 8 balls question before. I said 2 weighings. They asked how I knew. I said because the obvious answer is 3 weighings, 4v4, 2v2,1v1 but if the answer was that obvious asking the question would reveal nothing useful about me. I could easily see that the answer could not be 1 so I figured there was some tricky way that would let me accomplish the task in 2 weighings. I thought this was pretty clever of me and if I thought about the question a little bit longer I probably could have figured out that you 3v3 if the scales are equal you weigh the 2 unweighed balls. If the scales are not equal you weigh the 2 of the balls on the heavy side. The thing is the people interviewing me were HR professionals which meant that they were poorly equipped to deal with anything the least bit unusual so they failed to take notice of my genius.

posted by I Foody at 10:00 AM on June 30, 2011 [8 favorites]

posted by I Foody at 10:00 AM on June 30, 2011 [8 favorites]

Can someone point me to the "Doesn't like riddles, puzzles or math" checkbox on my LinkedIn profile?

posted by dyobmit at 10:03 AM on June 30, 2011 [1 favorite]

posted by dyobmit at 10:03 AM on June 30, 2011 [1 favorite]

The puzzle questions are a plague within silicon valley.

In theory, you're testing whether or not someone can apply their CS theory to a new and/or novel situation. In practice, all you're really doing is testing whether or not they've seen that puzzle before. On average, all you can really say about someone's correct answer to one of these is they're smart enough to have understood the answer they read/talked about from somewhere else (which isn't anything to sneeze at - many can't even do that).

I only ask two questions (with extended follow-ups) when I interview candidates: 1) tell me about a hard problem, in or out of the workplace and 2) tell me about a sucky situation from your work history. The first question lets me know what they think is hard, and what they did about it. If the problem is harder than I know what to do with, that gives them an opportunity to show me how well they can teach. The second question lets me know what they think sucks, and I follow up with what they did to make it suck less.

I can teach puzzle answers. I can't teach the desire to take on and deal with hard problems or sucky situations.

Oh, and the race horses need to be deterministically fast relative to one another over repeated races.

posted by NoRelationToLea at 10:03 AM on June 30, 2011 [9 favorites]

In theory, you're testing whether or not someone can apply their CS theory to a new and/or novel situation. In practice, all you're really doing is testing whether or not they've seen that puzzle before. On average, all you can really say about someone's correct answer to one of these is they're smart enough to have understood the answer they read/talked about from somewhere else (which isn't anything to sneeze at - many can't even do that).

I only ask two questions (with extended follow-ups) when I interview candidates: 1) tell me about a hard problem, in or out of the workplace and 2) tell me about a sucky situation from your work history. The first question lets me know what they think is hard, and what they did about it. If the problem is harder than I know what to do with, that gives them an opportunity to show me how well they can teach. The second question lets me know what they think sucks, and I follow up with what they did to make it suck less.

I can teach puzzle answers. I can't teach the desire to take on and deal with hard problems or sucky situations.

Oh, and the race horses need to be deterministically fast relative to one another over repeated races.

posted by NoRelationToLea at 10:03 AM on June 30, 2011 [9 favorites]

*I still don't get the stairs. I don't see how it's a fibonacci sequence, either. I get your formula, but I don't see how it gives you the answer. Whatever step x you're standing on, it's just S(n-x) + all of the other ones. How does that eventually give an answer?*

I'm not sure what "S(n-x) + all of the other ones" means precisely, but here's why the answer to the original question is the Fibonacci sequence:

S(1) (the number of ways to climb a 1-step staircase) is 1, obviously.

S(2) is 2; you can take one two-step step, or two one-step steps.

S(3) = S(1) + S(2) = 3; you can either start with a two-step step and then there are S(1) ways of going on from there, or take a one-step step and then there are S(2) ways of going on from there.

S(4) = S(2) + S(3) = 5, for the same reason.

You can see that this is generating the Fibonacci sequence 1, 1, 2, 3, 5, 8, 13...; also you can know that S(n) = S(n-1) + S(n-2) generates the Fibonacci sequence (given the right starting conditions).

posted by dfan at 10:05 AM on June 30, 2011 [1 favorite]

*If you walk into a liquor store to count the unsold bottles, but the clerk is screaming at you to leave, what do you do?*

This is not an interview question, this is a David Lynch movie.

posted by cottoncandybeard at 10:05 AM on June 30, 2011 [17 favorites]

In the 70s, I applied for a job at a convenience store. They gave me a lie detector test that asked, among things, if I had ever smoked marijuana. I didn't get the job. If only I had, I would have been saved from earning a Ph.D. I weep.

posted by Peach at 10:06 AM on June 30, 2011 [1 favorite]

posted by Peach at 10:06 AM on June 30, 2011 [1 favorite]

Also, the correct answer for all of these questions is "I Google it." You want to know how I solve a problem that is completely outside my area of expertise or interests? I Google it, and if that doesn't give me an answer, I find someone who can get me the answer.

How many tennis balls could fill a 747? There are few questions that could interest me less, and I have no interest in doing the math. Fuckin' Google It. What's the market for piano tuners in Chicago? Probably enough to keep as many piano tuners in business as there are in Chicago. You in the business of tuning pianos? You in the business of marketing piano tuners? No?

You say you're looking for an events manager. Here's a good question you can ask me to determine how I solve a problem: two of your weekend events staff have called in sick and Custodial didn't clean the venue as requested. Your assistant double-booked the venue and didn't mark the second booking in the calendar. What do you do?

The answer, I guarantee, has nothing to do with manhole covers.

posted by ten pounds of inedita at 10:07 AM on June 30, 2011 [10 favorites]

How many tennis balls could fill a 747? There are few questions that could interest me less, and I have no interest in doing the math. Fuckin' Google It. What's the market for piano tuners in Chicago? Probably enough to keep as many piano tuners in business as there are in Chicago. You in the business of tuning pianos? You in the business of marketing piano tuners? No?

You say you're looking for an events manager. Here's a good question you can ask me to determine how I solve a problem: two of your weekend events staff have called in sick and Custodial didn't clean the venue as requested. Your assistant double-booked the venue and didn't mark the second booking in the calendar. What do you do?

The answer, I guarantee, has nothing to do with manhole covers.

posted by ten pounds of inedita at 10:07 AM on June 30, 2011 [10 favorites]

I don't understand the liquor bottle question, either. Why am I there to count the unsold bottles - did someone assign me that task or is it just a hobby of mine? Most stores don't put their full inventory on display, so how could I get an accurate count of any unsold liquor? (I'm really craving a cocktail now, BTW.)

I was fortunate in that my very first job interview didn't include any of those goofy type questions; in fact the interviewer (who ended up being my boss) basically bantered with me for about 10 minutes, we exchanged a few jokes (I have a habit of making bad puns) and as I was leaving he asked "By the way, how's your typing?" (this was in 1976, the position was for a telex operator/general clerical position). I was 16 years old and I remember telling my Mom about the interview and her asking incredulously "He didn't give you a typing or shorthand test? He didn't ask for references or previous experience?" "Nope." She rolled her eyes and suggested that he was just using his position as a way to meet young girls and that there wasn't even a job opening.

posted by Oriole Adams at 10:07 AM on June 30, 2011 [1 favorite]

I was fortunate in that my very first job interview didn't include any of those goofy type questions; in fact the interviewer (who ended up being my boss) basically bantered with me for about 10 minutes, we exchanged a few jokes (I have a habit of making bad puns) and as I was leaving he asked "By the way, how's your typing?" (this was in 1976, the position was for a telex operator/general clerical position). I was 16 years old and I remember telling my Mom about the interview and her asking incredulously "He didn't give you a typing or shorthand test? He didn't ask for references or previous experience?" "Nope." She rolled her eyes and suggested that he was just using his position as a way to meet young girls and that there wasn't even a job opening.

posted by Oriole Adams at 10:07 AM on June 30, 2011 [1 favorite]

Here's my absolute favorite:

heyforfour: "

posted by yaymukund at 10:08 AM on June 30, 2011 [6 favorites]

heyforfour: "

*For a summer job at a (non-chain) print shop:*

"If you were a vegetable in a salad, what vegetable would you be?"

Followup: "You have been stabbed on a fork with some other pieces of salad and are rising upward toward a giant mouth. What do you do?"""If you were a vegetable in a salad, what vegetable would you be?"

Followup: "You have been stabbed on a fork with some other pieces of salad and are rising upward toward a giant mouth. What do you do?"

posted by yaymukund at 10:08 AM on June 30, 2011 [6 favorites]

What is it that has four pairs of pants, lives in Philadelphia, and it never rains but it pours?

posted by cottoncandybeard at 10:10 AM on June 30, 2011 [2 favorites]

posted by cottoncandybeard at 10:10 AM on June 30, 2011 [2 favorites]

Some of these are just vanilla computer science questions. I'm pretty sure we learned the Google stair problem in one of my college courses.

posted by yaymukund at 10:10 AM on June 30, 2011

posted by yaymukund at 10:10 AM on June 30, 2011

*"Is Stealing Wrong?"*

I applied for a job at Wal-Mart once (I was desperate) and before even allowing you the great privilege of an interview, there was a ridiculously long online questionnaire just full of inane questions like this that had to be passed first. The template for every question was this:

37. Hypothetical problem! Solution?

a. Go cry in the bathroom until your shift is over

b. Take responsibility and fix this thing

c. Run to your manager bawling and screaming

d. Exacerbate the problem just for fun while twiddling your villainous mustache (glue on evil mustaches available at front desk for female employees)

I have absolutely no idea what the correct approach was. I answered B. for almost everything (because

*yes*, if I discover someone bleeding to death in the toys aisle, I

*am*going to call 911) and I was fairly relieved to fail miserably. I don't want to work for anyone who wants me to be unable to make decisions myself or to be cartoonishly evil and I spend enough of my free time crying in bathrooms already, thanks.

posted by byanyothername at 10:11 AM on June 30, 2011 [2 favorites]

*In theory, you're testing whether or not someone can apply their CS theory to a new and/or novel situation. In practice, all you're really doing is testing whether or not they've seen that puzzle before.*

I dunno, I'm pretty good at solving puzzles like this without having encountered them before. On the other hand,

1) I'm good at them largely because I have seen hundreds of them and have internalized the basic tactics (e.g., for the staircase problem, it was clear that a dynamic programming approach would work, and then the answer pops out as soon as you start actually doing the work). Of course, internalizing hundreds of tactics for attacking math problems does come in handy as a programmer.

2) It's probably hard to distinguish between the people who have encountered the problem before and remember the solution and people who are figuring it out on the fly.

3) Asking one question like this is unlikely to generate meaningful information. It's like watching a baseball player take one at-bat and being disappointed that he doesn't get a hit.

posted by dfan at 10:11 AM on June 30, 2011

*how could I get an accurate count of any unsold liquor*

It's surprisingly trivial. You count the number of

*sold*bottles and subtract from the total.

posted by Wolfdog at 10:12 AM on June 30, 2011

quin: "

That's three weighings.

posted by notsnot at 10:15 AM on June 30, 2011

*"*

If you weigh 4/4, then takeIf you weigh 4/4, then take

*two*balls from each side, you get the answer in exactly 2 weighings every time. If the scales balance after removing two balls, you weigh the two heavy-side balls you removed; if scales don't balance, you weigh the two heavy-side balls left on the scaleThat's three weighings.

posted by notsnot at 10:15 AM on June 30, 2011

*VWR International: How would you market a telescope in 1750 when no one knows about orbits, moons, etc.?*

Well, I would sell it to navies and armies for scoping out the enemy, or maybe to landowners for surveying work - but of course they all had telescopes by then, considering that they were invented 142 years earlier (thank you Wikipedia!). I wouldn't market them to astronomers because the military and shipping interests have more money.

also, I'm pretty sure that everyone in 1750 BC knew about moons, what with that

*really big one*showing up in the sky most nights. When were orbits first postulated? a long time before Ptolemy, if I remember them right, though it took until Kepler to work out that the planets have heliocentric elliptical orbits.

posted by jb at 10:17 AM on June 30, 2011 [1 favorite]

*Goldman Sachs: Suppose you had eight identical balls. One of them is slightly heavier and you are given a balance scale. What’s the fewest number of times you have to use the scale to find the heavier ball?*

First, create a bet that you can't answer the question within 5 minutes. Leave the room to market this.

Second, determine the balance of bets, then take the long odds yourself.

Third, borrow money for #2, then make a bet that you can't pay it off. Market this.

Fourth, buy insurance on your debt, then buy shares of the reinsurance company. Bet against them.

Repeat until interviewers approve.

For bonus points, contact appropriate people to make sure taxpayers will cover losses should 1-

*n*run into problems.

posted by doctornemo at 10:21 AM on June 30, 2011 [33 favorites]

*Sell me an invisible pen.*

I'd put it in a collectible case. For my sales pitch I would hand it to them and say, "I have a pen only rich, beautiful and happy people can see. Would you like to open the box to examine it before purchase?"

*Twenty-five racehorses, no stopwatch, five tracks. Figure out the top three fastest horses in the fewest number of races.*

I get all the horses on one track and then chase after them on another horse with a gun. The 2 left in front and the one I'm riding are the fastest.

*What is your strategy at table tennis?*

To win by any means necessary.

*You are climbing a staircase. Each time you can either take one step or two. The staircase has n steps. In how many distinct ways can you climb the staircase?*

Infinite.

*How do you evaluate Subway’s five-foot long sub policy?*

I think it's crap. Give me $5 triple meat half-foots.

*How many cocktail umbrellas are there in a given time in the United States?*

Stupid

Would you be okay hearing “no” from seven out of 10 customers.

Would you be okay hearing “no” from seven out of 10 customers.

Depends on what they are saying NO to.

*Suppose you had eight identical balls. One of them is slightly heavier and you are given a balance scale. What’s the fewest number of times you have to use the scale to find the heavier ball?*

0. I am an expert ball handler. I would cup each ball and determine the heaviest.

*Estimate how many planes are there in the sky.*

1/3rd.

*If you could describe Hershey, Godiva and Dove chocolate as people, how would you describe them?*

Fat, boring and melt under pressure.

*If I was a genie and could give you your dream job, what and where would it be?*

THIS ONE, OF COURSE, GENIE. I'd like to be a demi-god. Earth.

*What did you play with as a child?*

LEGO.

*What did you play with as an adult?*

LEGO.

*How would you market a telescope in 1750 when no one knows about orbits, moons etc.*Examine the heavens with your own eyes!

*How would you rate your life on a scale of 1 to 10?*

What am I rating? I'll choose 3, I like 3.

*What is the smallest number divisible by 225 that consists of all 1’s and 0’s?*

11111111100

*If we were playing Russian roulette and had one bullet, I randomly spun the chamber and fired but nothing was fired. Would you rather fire the gun again or respin the chamber and then fire on your turn?*

Spin. That. Chamber.

*Tell me about your life from kindergarten onwards.*

Finished school. Did a lot of awesome stuff. Traveled the world. Made a lot of money. Gave away a lot of money. Climbed a lot of stuff. Made a lot of beauty. Had wonderful times with loved ones.

*Five guys, all of different ages, enter a bar and take a seat at a round table. What is the probability that they are seated in ascending order of age?*1/12?

posted by zephyr_words at 10:23 AM on June 30, 2011

*You say you're looking for an events manager. Here's a good question you can ask me to determine how I solve a problem: two of your weekend events staff have called in sick and Custodial didn't clean the venue as requested. Your assistant double-booked the venue and didn't mark the second booking in the calendar. What do you do?*

Hey, that's my actual job! Lemme take a swing:

(1) Call Custodial and see if they have a recommendation for a day-of onsite cleaning crew; a lot of caterers, big venue events, etc., use services like this. You're looking for a bunch of people who will walk around the venue all night taking out trash and using brooms. This is not ideal, but will at least pick up some slack. If they don't have a recommendation, find somebody to call myself. Custodial gets a write-up.

(2) Call all my other weekend staff to see if anybody can pick up a shift. Then start calling non-weekend staff. Then start calling house managers to see if they can pick up a shift. Then start calling volunteers in order of seniority. Then start asking if anybody has trustworthy friends that can work as a one-day contractor.

(3) Call the second-booked act and give them a brief on the situation. I didn't figure out that the venue was double-booked until the day of? I've somehow been selling tickets to two overlapping events on the same day? Okay, whatever. If it's possible to move up the first show and delay the second, do that. If it's not possible, are there other venues in the area that could take a booking that night? In my area, I have a couple I might be able to foist them on to if it's not a really busy night. You could contract with them, move the second show there, and eat the sub-contracted venue cost (my predecessor had to actually do this once, although it wasn't the day-of; we still owe our local performing arts center a favor). Worst case scenario, you cancel the second show, turn people away at the door (or offer a trade for tickets to the real show, if that's feasible, although there are dozens of reasons why it might not be [reserved seats, to name one]), and offer to reschedule at literally any available time that the second act may have in their routing. You are at their mercy now, and you're fucked no matter what happens.

(4) Fire your assistant. No, wait: devise a way to super-fire your assistant, and then do that. Didn't mark it in the booking calendar? Didn't even apparently CHECK the booking calendar, because there was already an event there? Somehow allowed two shows to go to contract while having the same date? Seriously? There are almost no unforgivable mistakes in events, IMO, because the whole job is improvised anyway, but the only think you must ALWAYS do is keep a clean booking calendar. Assistant is super-fired, and in the exit interview a great deal of time should be devoted to figuring out just how such a colossal fuck-up could have occurred.

posted by penduluum at 10:25 AM on June 30, 2011 [15 favorites]

*"Is Stealing Wrong?"*

I had a similar questionnaire when applying at an unnamed chain store. Stand out questions were:

"If you found our your mother was stealing office supplies, would you report her to her boss?"

Which is incredibly stupid. Because even if you're the type of person who considers themselves highly moral you're probably going to try to get your mother to return the items and stop stealing instead of going directly to her boss. And there's no nuance possible in the answers.

"Have you ever thought about breaking the law?"

This one's awesome because after reading the question, how could you not? Also, if you know anything about the law, you know that you pretty much have to break it every day, just to function.

Of course they're not looking for correct answers. They're looking for the ability to determine what bullshit people want to be fed so that they'll buy the overpriced extra "coverage" on their 60" plasma TV.

*How is the Russian Roulette one different from Monty Haul?*

There's no prize at the end.

posted by ODiV at 10:27 AM on June 30, 2011

Most "out there" question I ever had was "Estimate the number of dogs in the city of Toronto. Tell me your thought process in getting to that estimate" - the answer I *wanted* to give was "Something more than 1, and less than a billion. Because I have a dog, and I live in Toronto, so that's at least 1. And I'm pretty sure I'm not the only dog owner in the city. And the city doesn't seem to be overrun with dogs, hence my comfortable upper bound of 'less than a billion'" - instead I had a sort of handwavey half-assed answer to the question, because at this point I already knew I didn't want to work for them.

posted by antifuse at 10:28 AM on June 30, 2011

posted by antifuse at 10:28 AM on June 30, 2011

I hate those personality tests, because they frequently include the question 'do you read all the information that comes with your prescriptions?' as a ringer question to see if you're just answering questions like they think you should. See, apparently no one reads all that information, so it's easy to use as a weed-out question.

The problem is that I DO read all the information that comes with my prescriptions, so when I am truthful I get dinged as a liar. There are all kinds of questions like that on those tests.

posted by winna at 10:32 AM on June 30, 2011 [7 favorites]

The problem is that I DO read all the information that comes with my prescriptions, so when I am truthful I get dinged as a liar. There are all kinds of questions like that on those tests.

posted by winna at 10:32 AM on June 30, 2011 [7 favorites]

*Now, I take the gun, spin the chamber, place the barrel against my head, and pull the trigger.*

Nothing happens.

Assuming you wish to live, is it better to spin the chamber again, or not?

Nothing happens.

Assuming you wish to live, is it better to spin the chamber again, or not?

Doesn't matter. If I spin, I get even odds for an empty barrel. However, your spin also had a 50/50 chance of getting on barrel that was preceding an empty barrel. Right?

posted by Nonsteroidal Anti-Inflammatory Drug at 10:36 AM on June 30, 2011

*See, apparently no one reads all that information, so it's easy to use as a weed-out question.*

As a fellow label reader, several events in my childhood suddenly make a lot more sense.

posted by Nonsteroidal Anti-Inflammatory Drug at 10:37 AM on June 30, 2011 [1 favorite]

I do what experience and adventure games have thought me. Click on everything. Twice.

posted by The Whelk at 10:37 AM on June 30, 2011 [4 favorites]

posted by The Whelk at 10:37 AM on June 30, 2011 [4 favorites]

*Assuming you wish to live, is it better to spin the chamber again, or not?*

If the previous pull was safe, then the current chamber has a 1/3 chance of having a bullet.

If you spin, the current chamber has a 1/2 chance of having a bullet.

So don't spin the chamber. And point the gun at the other guy, pulling the trigger three times.

posted by ten pounds of inedita at 10:46 AM on June 30, 2011 [1 favorite]

Once, the answer is once. You're trying to find the minimum number of times, not the best average. If you put one ball on each side of the balance and the balance isn't even, then you've found the heavy ball. If you're lucky, this can happen on the first try.

posted by tracknode at 10:47 AM on June 30, 2011 [3 favorites]

So back when I was in 8th grade, I was doing an interview for a certain private college prep high school (yes, really... sad I know). Said school got a large number of applicants and had a rather high opinion of itself at the time, so instead of doing individual interviews when prospective students came to visit, they had a couple of cattle-call interview days on the weekend where most of the faculty would show up and interview students all day long. Worse yet, they are pair interviews, meaning they stick you with some random kid and interview you together. This is a terrible way to conduct interviews, especially of 8th graders, and looking at their website right now, I'm saddened to see that they still do this.

Anyway, I'm there and they dump me with some fresh guidance counselor and another kid who, frankly, seemed to be a bit of a dolt. Actually, that's not really fair. He probably thought I was a dolt too; that's what happens when you stuff 13-year-old strangers in a room and make them interview together. Most of the high schools asked questions about extracurricular activities, academic interests, favorite and last favorite subjects, that kind of thing. You'd get some "tell me about your ideal day" types of questions, but at least that's in the getting to know you realm.

But this school wanted to be a bit more edgy, so the interviewers were furnished with a list of abstract questions to ask. The fresh-faced guidance counselor (well, it wasn't all that fresh anymore after six hours of interviewing 8th graders) asks me and dolt-boy: "say you're going to a deserted island. You'll have food and shelter and other necessities already, so what personal things do you take with you?"

I'm a bit thrown and start to consider options. Of course now I'd probably start with "a case of scotch, a case of sunscreen, a case of the trashiest fiction known to mankind (Dirk Pitt novels, naturally), and someone to massage my shoulders until my back falls off," but give me a break; I was 13. At the time, my main concern was how to use this absurd interview format to work in anything about my strengths and activities. I remember thinking: "what am I supposed to say? Well, if I were to go to a deserted island, I would be sure to take long my award-winning science fair project so I could admire it. Let me tell you about it..."

The strangest part of this moronic interview was that, presumably in an effort to make us feel more comfortable or maybe just to waste as much of our time as possible, the interviewers were instructed to answer the questions for themselves after we did. I can assure you that however little that guidance counselor cared about my deserted island supplies, I cared about hers a whole lot less.

I did wind up getting in, though I didn't accept, but I suspect that had more to do with the fact that during my visit, I wound up crawling on the floor of the admissions office to fix their printer in order to print off some paperwork.

posted by zachlipton at 10:48 AM on June 30, 2011

Anyway, I'm there and they dump me with some fresh guidance counselor and another kid who, frankly, seemed to be a bit of a dolt. Actually, that's not really fair. He probably thought I was a dolt too; that's what happens when you stuff 13-year-old strangers in a room and make them interview together. Most of the high schools asked questions about extracurricular activities, academic interests, favorite and last favorite subjects, that kind of thing. You'd get some "tell me about your ideal day" types of questions, but at least that's in the getting to know you realm.

But this school wanted to be a bit more edgy, so the interviewers were furnished with a list of abstract questions to ask. The fresh-faced guidance counselor (well, it wasn't all that fresh anymore after six hours of interviewing 8th graders) asks me and dolt-boy: "say you're going to a deserted island. You'll have food and shelter and other necessities already, so what personal things do you take with you?"

I'm a bit thrown and start to consider options. Of course now I'd probably start with "a case of scotch, a case of sunscreen, a case of the trashiest fiction known to mankind (Dirk Pitt novels, naturally), and someone to massage my shoulders until my back falls off," but give me a break; I was 13. At the time, my main concern was how to use this absurd interview format to work in anything about my strengths and activities. I remember thinking: "what am I supposed to say? Well, if I were to go to a deserted island, I would be sure to take long my award-winning science fair project so I could admire it. Let me tell you about it..."

The strangest part of this moronic interview was that, presumably in an effort to make us feel more comfortable or maybe just to waste as much of our time as possible, the interviewers were instructed to answer the questions for themselves after we did. I can assure you that however little that guidance counselor cared about my deserted island supplies, I cared about hers a whole lot less.

I did wind up getting in, though I didn't accept, but I suspect that had more to do with the fact that during my visit, I wound up crawling on the floor of the admissions office to fix their printer in order to print off some paperwork.

posted by zachlipton at 10:48 AM on June 30, 2011

*How is the Russian Roulette one different from Monty Haul?*

The Monty Haul problem involves a fox, a chicken, a sack of corn, and a truck.

*How many cocktail umbrellas are there in a given time in the United States?*

Stupid

Stupid

Not really stupid. The solution involves estimates, which tend to be off in both directions, so the errors cancel. It's like estimating a restaurant bill. They want the person who will make some rough calculations, as opposed to the person who guesses out of the blue, or the person who says it's impossible to know.

posted by weapons-grade pandemonium at 10:48 AM on June 30, 2011

Nonsteroidal. I am afraid you can do better than 50/50. Read this answer to see how.

posted by LoopyG at 10:49 AM on June 30, 2011

posted by LoopyG at 10:49 AM on June 30, 2011

Giles Turnbull made me laugh out loud.

posted by probably not that Karen Blair at 10:52 AM on June 30, 2011

posted by probably not that Karen Blair at 10:52 AM on June 30, 2011

Ah. I missed that response, but that makes sense.

This is why I don't point guns at my head.

posted by Nonsteroidal Anti-Inflammatory Drug at 10:52 AM on June 30, 2011

This is why I don't point guns at my head.

posted by Nonsteroidal Anti-Inflammatory Drug at 10:52 AM on June 30, 2011

Don't get discouraged. Pointing guns at ones own head has its advantages! Like... um.... maths!

posted by LoopyG at 10:53 AM on June 30, 2011

posted by LoopyG at 10:53 AM on June 30, 2011

*if you know anything about the law, you know that you pretty much have to break it every day, just to function.*

Hi there. I'm a lawyer. You either don't know anything about the law, or you have an unusual sense of what it means "just to function." Better luck tomorrow!

posted by red clover at 11:00 AM on June 30, 2011 [1 favorite]

*What’s the fewest number of times you*

Once, the answer is once. You're trying to find the minimum number of times, not the best average. If you put one ball on each side of the balance and the balance isn't even, then you've found the heavy ball. If you're lucky, this can happen on the first try.

**have to**use the scale to find the heavier ball?Once, the answer is once. You're trying to find the minimum number of times, not the best average. If you put one ball on each side of the balance and the balance isn't even, then you've found the heavy ball. If you're lucky, this can happen on the first try.

(emphasis on the original question mine)

No, you're trying to find the minimum number of weighings that guarantee you have an answer. If I asked you how many times you would have to blind pull a marble out of an urn that has 6 red and 6 blue marbles in it before you got a blue marble, would you answer 1? (Hint: If you did, you'd be wrong.)

posted by kmz at 11:02 AM on June 30, 2011 [1 favorite]

kmz, I read the question just as tracknode did. I don't see where they ask for a guarantee.

posted by annsunny at 11:06 AM on June 30, 2011

posted by annsunny at 11:06 AM on June 30, 2011

Ah, that's a good point kmz. FWIW, I got this question at a job interview, answered once, and got the job.

posted by tracknode at 11:08 AM on June 30, 2011

posted by tracknode at 11:08 AM on June 30, 2011

*What’s the fewest number of times you have to use the scale to find the heavier ball?*.

If this is for an engineering position, the answer is

**I**will use the scale zero times. I'll just get one of the techs to do it for me.

posted by jefbla at 11:17 AM on June 30, 2011

*I do what experience and adventure games have thought me. Click on everything. Twice.*

You kids these days with your newfangled video adventure games.

In my day, we

*guessed every verb.*Twice.

posted by Zed at 11:24 AM on June 30, 2011 [4 favorites]

Unless the liquor store sells on consignment, all the bottles have already been sold by the distributor to the store. So there are no unsold bottles in a liquor store.

posted by The World Famous at 11:26 AM on June 30, 2011 [3 favorites]

posted by The World Famous at 11:26 AM on June 30, 2011 [3 favorites]

*Capital One: How do you evaluate Subway’s five-foot long sub policy?*

I'm not sure I would bicker over the fine points of any of these questions. The article is suffering from at least one word-of-mouth ("game of telephone") type error: I am certain the real question CapitalOne asked was actually, "How do you evaluate Subway's

*five-dollar foot-long*sub policy?"

Also, c'mon, these aren't "crazy" questions; for the most part they're just math problems. All of these seem like things you'd ask a math or CS major whose skills in translating real-world problems into quantitative solutions are important. (I bet none of these questions are being asked to people applying for loan underwriter, marketing, HR, or custodial positions in these companies.) They would only seem "crazy" to someone who has never taken a math class past the 7th grade or has never written computer code.

(This also seems like the sort of article that my retired dad would send me a link to. Which is to say I am dubious about its "best of the web"-ness.)

posted by aught at 11:30 AM on June 30, 2011

*The Monty Haul problem involves a fox, a chicken, a sack of corn, and a truck.*

Kill the chicken, marry the sack of corn? I'm not sure what the truck is for... wait. Let me start over.

posted by Wolfdog at 11:32 AM on June 30, 2011 [1 favorite]

*So back when I was in 8th grade, I was doing an interview for a certain private college prep high school*

Same here, except I was in 6th grade and the school was a 7-12 prep school. I toured the campus, talked to some teachers, and finally had a one-on-one with the middle school headmaster, a native of Zimbabwe, in his office. I don't remember what we were talking about, except that we were standing and he was pacing a bit, and I remember looking over at a shelf of trophies with a soccer ball on it. As we're talking, and he's pacing, he suddenly grabs the soccer ball off the shelf and lobs it at me from about three feet away. I instinctively chest it down to my feet and then stare at him. He says, "Excellent!" I am accepted for admission.

posted by Errant at 11:39 AM on June 30, 2011 [5 favorites]

But why are you playing [Russian roulette],Because you've been posted to bumfuck Siberia for ten years with two people you loathe, and the prospect of a bloody messy death is seeming more and more preferable to staying where you are.

The fact that the interviewer thinks it's a reasonable question gives you an idea of the nature of the job you are interviewing for.

posted by hattifattener at 11:43 AM on June 30, 2011 [4 favorites]

Read literally, aren't all numbers technically divisible by 225? Divisible to give you a whole number, on the other hand...

posted by jmd82 at 11:45 AM on June 30, 2011

posted by jmd82 at 11:45 AM on June 30, 2011

*How is the Russian Roulette one different from Monty Haul?*

How is the Monty Haul one different from Monty Hall?

posted by kingbenny at 11:52 AM on June 30, 2011 [2 favorites]

*What is your strategy at table tennis?*

Attack. Defensive players rarely win against a competent player. Observe your opponent's receiving stance when on serve; if they leave one side of the table a little more open, it is because they trust their strike on that side and are trying to bait you into serving to their strength. Perceive them instead as covering their weaker side and go there as much as possible. Don't waste time and reflex watching where your shot goes; once you hit it, it's out of your hands, so get ready for the next shot. Aim for the body; some people get scared when a ball comes at them. Switch striking speeds so that you can create and then disrupt your opponent's rhythm. Play fast when ahead, slower when behind; do not give your opponent time to recover but create that time for yourself. Get a better paddle. Play a lot.

posted by Errant at 11:55 AM on June 30, 2011 [5 favorites]

The 225 question in ten digits:

11100001.00 (binary)

posted by dances_with_sneetches at 11:57 AM on June 30, 2011

11100001.00 (binary)

posted by dances_with_sneetches at 11:57 AM on June 30, 2011

If you're still scratching your head on the staircase thing, let me try and make my solution a bit more explicit. If you want to climb a staircase with n steps, you can split the "ways" that you do this into 2 groups: one group consists of the ones that start with you taking a single step, and the other group consists of the ones where you start with a double-step.

After you've taken the first single step, there are n-1 steps left to ascend, and we know there are S(n-1) ways to do that; so there must be S(n-1) "ways" in that first group. On the other hand, if you took a double-step first, there are n-2 steps left to ascend, and we know there are S(n-2) ways to do that; so there must be S(n-2) "ways" in that second group.

So, S(n-1) + S(n-2) total ways (group one ways plus group 2 ways) for the n step staircase.

posted by King Bee at 11:58 AM on June 30, 2011 [1 favorite]

After you've taken the first single step, there are n-1 steps left to ascend, and we know there are S(n-1) ways to do that; so there must be S(n-1) "ways" in that first group. On the other hand, if you took a double-step first, there are n-2 steps left to ascend, and we know there are S(n-2) ways to do that; so there must be S(n-2) "ways" in that second group.

So, S(n-1) + S(n-2) total ways (group one ways plus group 2 ways) for the n step staircase.

posted by King Bee at 11:58 AM on June 30, 2011 [1 favorite]

*Read literally, aren't all numbers technically divisible by 225?*

I know you are just being cute, but "divisible by

*n*" really does specifically mean "can be divided by

*n*without leaving a remainder".

posted by dfan at 11:58 AM on June 30, 2011 [3 favorites]

I'm not good at these, but I don't think I've seen the answer I came up with for the Russian Roulette. If you have, and I missed it, I apologize.

I say spin the barrel because: If you don't spin you have an 80% chance of hitting an empty chamber (4/5), but if you do spin you have an 83% +/- (5/6) chance of an empty chamber.

posted by Benny Andajetz at 12:04 PM on June 30, 2011

I say spin the barrel because: If you don't spin you have an 80% chance of hitting an empty chamber (4/5), but if you do spin you have an 83% +/- (5/6) chance of an empty chamber.

posted by Benny Andajetz at 12:04 PM on June 30, 2011

*I'm not sure what the truck is for... wait. Let me start over.*

How is the Monty Haul one different from Monty Hall?

How is the Monty Haul one different from Monty Hall?

That's where the truck comes in, silly.

posted by weapons-grade pandemonium at 12:07 PM on June 30, 2011

*Capital One: How do you evaluate Subway’s five-foot long sub policy?*

WTF does this question even

*mean*?

posted by Benny Andajetz at 12:10 PM on June 30, 2011 [2 favorites]

*I'm not good at these, but I don't think I've seen the answer I came up with for the Russian Roulette.*

When solving problems like this, I find it useful to exaggerate the conditions. Suppose, for example, there are five bullets in the revolver, and one blank chamber. If you spin to the blank chamber and pull the trigger, the next time would you choose to pull the trigger, or spin again?

posted by weapons-grade pandemonium at 12:13 PM on June 30, 2011

WTF does this question even mean?

posted by Benny Andajetz at 3:10 PM on June 30 [+] [!]

I think they mean 5 Dollar Foot Long. It is still a weird question.

As for the scale problem - the answer is 1. Remeber the question is "What’s the fewest number of times you have to use the scale to find the heavier ball?"

You randomly pick two (identical? I think not) balls. One of them happens to be heavier. You got lucky. That is the fewest amount of times you have to weigh stuff. No one said anything about if this was the most effective strategy to always get the heavy ball.

posted by Sk4n at 12:20 PM on June 30, 2011

posted by Benny Andajetz at 3:10 PM on June 30 [+] [!]

I think they mean 5 Dollar Foot Long. It is still a weird question.

As for the scale problem - the answer is 1. Remeber the question is "What’s the fewest number of times you have to use the scale to find the heavier ball?"

You randomly pick two (identical? I think not) balls. One of them happens to be heavier. You got lucky. That is the fewest amount of times you have to weigh stuff. No one said anything about if this was the most effective strategy to always get the heavy ball.

posted by Sk4n at 12:20 PM on June 30, 2011

You have a weird definition of "have to", Sk4n. If the question said "might have to" instead of "have to" I would agree with you. Clearly some of these questions could be worded better, though.

posted by dfan at 12:28 PM on June 30, 2011

posted by dfan at 12:28 PM on June 30, 2011

*What is the smallest number divisible by 225 that consists of all 1’s and 0’s?*

Where is everyone getting the huge numbers? 225 x 4 = 1100.

posted by Benny Andajetz at 12:31 PM on June 30, 2011 [2 favorites]

225 x 4 = 900.

posted by dfan at 12:31 PM on June 30, 2011 [1 favorite]

posted by dfan at 12:31 PM on June 30, 2011 [1 favorite]

*225 x 4 = 900*

Well, there you go. No wonder my checkbook doesn't balance.

posted by Benny Andajetz at 12:33 PM on June 30, 2011 [1 favorite]

*You want to know how I solve a problem that is completely outside my area of expertise or interests? I Google it, and if that doesn't give me an answer, I find someone who can get me the answer.*

Good policy for managers. Bad idea for neurosurgeons, bridge designers or crane operators.

posted by Dr Dracator at 12:36 PM on June 30, 2011 [1 favorite]

"Hmm, that's a really intriguing question. You know, I consider myself a team player and a collaborative thinker, and I value the wisdom of my mentors. With that in mind, I'd like to hear how you'd solve this."

posted by Metroid Baby at 12:36 PM on June 30, 2011 [2 favorites]

posted by Metroid Baby at 12:36 PM on June 30, 2011 [2 favorites]

*Citigroup: What is your strategy at table tennis?*

A strange game. The only winning move is not to play.

posted by DevilsAdvocate at 12:36 PM on June 30, 2011 [2 favorites]

I see what I did - I forgot to carry the two hundred. :)

posted by Benny Andajetz at 12:36 PM on June 30, 2011

posted by Benny Andajetz at 12:36 PM on June 30, 2011

*Good policy for managers. Bad idea for neurosurgeons, bridge designers or crane operators.*

What? No it's not. If my surgeon doesn't know how to handle the really specific thing that just went wrong, I want him to go pull up PubMed and be damned certain he's positive before he starts cutting. Similarly, if my bridge designer doesn't know the tensile strength of this particular mix of concrete, I'm more than OK with him checking it on the 'net rather than making assumptions that are off by an order of magnitude, and then hoping that his many wildass guesses will somehow use the law of averages to land him directly on the right answer.

posted by Mayor West at 12:41 PM on June 30, 2011

Why I am no longer working in business:

- Don't be so fucking stupid.

- Ooh, I love puzzles like this! I need to be slightly drunk to do them, though. Any scotch around here? How about that bottom drawer? Come on, don't be shy. You look like a secret tippler to me. Hell, I would be if I had to ask interview questions like this one.

- Try to hit the little ball so the other guy fails to make a legal return more often than he does that to me.

- The number of

- I have no idea what you're talking about.

- Who the fuck cares? Is this the kind of mindless shit you people think about here? Forget it, I'm out of here. Bye.

- Sure, although I'd prefer hearing it from all ten. And how come you don't know about question marks, you punk illiterate?

*Suppose you had eight identical balls. One of them is slightly heavier and you are given a balance scale. What’s the fewest number of times you have to use the scale to find the heavier ball?*

- Ah come on, everyone knows this one. TWO. You might as well ask me about the fox, the chicken and the bag of corn. The fact that you're still trotting out this ancient old puzzler inclines me to think your company isn't that great at staying ahead of the curve. Bye!

- A plane has only two dimensions, by definition. Given that "the sky" is an indeterminate three-dimensional space then clearly the number of planes in the sky is infinite.

- Fat Prole, Fat Woman and I've never heard of Dove chocolate so I'll just say Fat Bastard.

- Oh, this one.

- *Level stare*. Do you really want to go there?

- Dude! Check this out! Look through this thing and you can see Miss Bodice's tits from all the way across the field! Okay, yeah, she's upside down, but still! Come awn!

*If you walk into a liquor store to count the unsold bottles, but the clerk is screaming at you to leave, what do you do?*

- Ask him what the fuck his problem is.

- 1 to 10

- Pass. That one's too hard to do just like that. Come on. Be reasonable.

- I'd rather not be the kind of unemployable loony who would play Russian roulette in the first place.

- I never went to kindergarten, you presumptuous bounder.

- Depends on who sits down before whom, doesn't it?

posted by Decani at 12:44 PM on June 30, 2011 [2 favorites]

*Sell me an invisible pen.*- Don't be so fucking stupid.

*Twenty-five racehorses, no stopwatch, five tracks. Figure out the top three fastest horses in the fewest number of races.*- Ooh, I love puzzles like this! I need to be slightly drunk to do them, though. Any scotch around here? How about that bottom drawer? Come on, don't be shy. You look like a secret tippler to me. Hell, I would be if I had to ask interview questions like this one.

*What is your strategy at table tennis?*- Try to hit the little ball so the other guy fails to make a legal return more often than he does that to me.

*You are climbing a staircase. Each time you can either take one step or two. The staircase has n steps. In how many distinct ways can you climb the staircase?*- The number of

*distinct ways*a human being can climb a staircase is infinite. Obviously. Isn't that obvious to you? It's obvious to me. Do I need to explain it to you?*How do you evaluate Subway’s five-foot long sub policy?*- I have no idea what you're talking about.

*How many cocktail umbrellas are there in a given time in the United States?*- Who the fuck cares? Is this the kind of mindless shit you people think about here? Forget it, I'm out of here. Bye.

*Would you be okay hearing “no” from seven out of 10 customers.*- Sure, although I'd prefer hearing it from all ten. And how come you don't know about question marks, you punk illiterate?

- Ah come on, everyone knows this one. TWO. You might as well ask me about the fox, the chicken and the bag of corn. The fact that you're still trotting out this ancient old puzzler inclines me to think your company isn't that great at staying ahead of the curve. Bye!

*Estimate how many planes are there in the sky.*- A plane has only two dimensions, by definition. Given that "the sky" is an indeterminate three-dimensional space then clearly the number of planes in the sky is infinite.

*If you could describe Hershey, Godiva and Dove chocolate as people, how would you describe them?*- Fat Prole, Fat Woman and I've never heard of Dove chocolate so I'll just say Fat Bastard.

*If I was a genie and could give you your dream job, what and where would it be?*- Oh, this one.

*Definitely.**Yawn*. Come on, son. Let's not insult each other's intelligence, eh?*What did you play with as a child?*- *Level stare*. Do you really want to go there?

*How would you market a telescope in 1750 when no one knows about orbits, moons etc.*- Dude! Check this out! Look through this thing and you can see Miss Bodice's tits from all the way across the field! Okay, yeah, she's upside down, but still! Come awn!

- Ask him what the fuck his problem is.

*How would you rate your life on a scale of 1 to 10?*- 1 to 10

*what*?*What is the smallest number divisible by 225 that consists of all 1’s and 0’s?*- Pass. That one's too hard to do just like that. Come on. Be reasonable.

*If we were playing Russian roulette and had one bullet, I randomly spun the chamber and fired but nothing was fired. Would you rather fire the gun again or respin the chamber and then fire on your turn?*- I'd rather not be the kind of unemployable loony who would play Russian roulette in the first place.

*Tell me about your life from kindergarten onwards.*- I never went to kindergarten, you presumptuous bounder.

*Five guys, all of different ages, enter a bar and take a seat at a round table. What is the probability that they are seated in ascending order of age?*- Depends on who sits down before whom, doesn't it?

posted by Decani at 12:44 PM on June 30, 2011 [2 favorites]

The 225 question in three digits. 1.00 (base 225)

posted by dances_with_sneetches at 12:47 PM on June 30, 2011 [2 favorites]

posted by dances_with_sneetches at 12:47 PM on June 30, 2011 [2 favorites]

*Sell me an invisible pen.*

Here you go. I'll have my billing department send you an invoice.

posted by The World Famous at 12:50 PM on June 30, 2011

*How many cocktail umbrellas are there in a given time in the United States?*

Recipe for a Gin n' Thyme (the interviewer misspoke):

-3 fingers Gin

-3 sprigs thyme

-splash of vermouth

-3 (three) cocktail umbrellas

posted by obscurator at 1:07 PM on June 30, 2011

**dances_with_sneetches**, 1.00 in base 225 is 1 in base 10. You meant 10 (base 225).

posted by King Bee at 1:10 PM on June 30, 2011 [1 favorite]

One way to approach coin-weighing problems is to identify a lower bound, based on how many possible outcomes there are for each weighing, and how many possible solutions you have to distinguish between.

For example, with a traditional balance scale there's three possible outcomes (left heavy, right heavy, balanced), so with n weighings you can distinguish between, at most, 3

So the problem given here, find one heavy coin among eight, you can set a lower bound of two weighings, because one weighing can distinguish only between three possibilities (3

Likewise, with the traditional "find one counterfeit coin among twelve; the counterfeit may be lighter or heavier than the real ones," you can immediately set three as as lower bound on the number of weighings (24 possibilities, 3

This is useful for coin-weighing problems if you haven't heard the particulars before. For example, if you have 19 coins, at least 2 but no more than 5 of which are counterfeit, and the counterfeit coins may be either heavier or lighter than the real ones (but the counterfeit ones all weigh the same), you can establish 10 as a lower bound on the number of weighings required [left as an exercise for the reader]. So you a) know not to waste your time looking for a solution with fewer than 10 weighings, and b) if you do find a solution with 10 weighings, you know you're done. It doesn't guarantee a solution with only 10 weighings is possible, however.

posted by DevilsAdvocate at 1:40 PM on June 30, 2011 [3 favorites]

For example, with a traditional balance scale there's three possible outcomes (left heavy, right heavy, balanced), so with n weighings you can distinguish between, at most, 3

^{n}possibilities. Then do the work to see if that lower bound is actually achievable—it often is, but not always.So the problem given here, find one heavy coin among eight, you can set a lower bound of two weighings, because one weighing can distinguish only between three possibilities (3

^{1}=3), but two weighings can distinguish between as many as nine possibilities (3^{2}=9). And in fact you can find one heavy coin among nine with two weighings.Likewise, with the traditional "find one counterfeit coin among twelve; the counterfeit may be lighter or heavier than the real ones," you can immediately set three as as lower bound on the number of weighings (24 possibilities, 3

^{3}=27), and in fact three is achievable.This is useful for coin-weighing problems if you haven't heard the particulars before. For example, if you have 19 coins, at least 2 but no more than 5 of which are counterfeit, and the counterfeit coins may be either heavier or lighter than the real ones (but the counterfeit ones all weigh the same), you can establish 10 as a lower bound on the number of weighings required [left as an exercise for the reader]. So you a) know not to waste your time looking for a solution with fewer than 10 weighings, and b) if you do find a solution with 10 weighings, you know you're done. It doesn't guarantee a solution with only 10 weighings is possible, however.

posted by DevilsAdvocate at 1:40 PM on June 30, 2011 [3 favorites]

*What is it that has four pairs of pants, lives in Philadelphia, and it never rains but it pours?*

Atsa good one, I give you three guesses.

posted by nathancaswell at 1:47 PM on June 30, 2011 [2 favorites]

Buy this invisible pen, fuckers, or it's Russian Roulette time.

posted by Astro Zombie at 1:59 PM on June 30, 2011 [5 favorites]

posted by Astro Zombie at 1:59 PM on June 30, 2011 [5 favorites]

**winna**writes

*"The problem is that I DO read all the information that comes with my prescriptions, so when I am truthful I get dinged as a liar. There are all kinds of questions like that on those tests."*

That's what that question is checking?! Heck I not only read everything that comes with my drugs, which after all is the minimum the law and liability makes prudent for the manufacturer to include, I also go on line to see what the manufacturer's site says and to google the drug.

posted by Mitheral at 2:05 PM on June 30, 2011

I already sold you an invisible pen, using an inaudible pitch.

posted by kenko at 2:07 PM on June 30, 2011 [2 favorites]

posted by kenko at 2:07 PM on June 30, 2011 [2 favorites]

My invisible pen's better than your invisible penis.

posted by Benny Andajetz at 2:18 PM on June 30, 2011

posted by Benny Andajetz at 2:18 PM on June 30, 2011

*What is it that has four pairs of pants, lives in Philadelphia, and it never rains but it pours?*

The Oregon Avenue Octopi?

posted by madcaptenor at 2:24 PM on June 30, 2011

A few years ago I was applying for a summer job at Staples. I had to fill out an online application form and there were the numerous multiple-choice questions. One went something like this:

How much merchandise/office supplies have you taken from your employers over the past 10 years?

a. none.

b. Less than $100

c. $101 - $1000

d. $1001 - $10000

e. $10001 or more

Another question asked if I had ever been involved in a physical altercation with a coworker. Yikes.

posted by dhens at 3:01 PM on June 30, 2011

How much merchandise/office supplies have you taken from your employers over the past 10 years?

a. none.

b. Less than $100

c. $101 - $1000

d. $1001 - $10000

e. $10001 or more

Another question asked if I had ever been involved in a physical altercation with a coworker. Yikes.

posted by dhens at 3:01 PM on June 30, 2011

*e. $10001 or more*

I assume that choice puts you on the fast track to management.

posted by Iridic at 3:02 PM on June 30, 2011 [2 favorites]

*Heck I not only read everything that comes with my drugs, which after all is the minimum the law and liability makes prudent for the manufacturer to include, I also go on line to see what the manufacturer's site says and to google the drug.*

Apparently there are not as many of us as you'd think, considering. It's like when the doctor asks if you drink, and no matter what you say they put 1-3 drinks a week.

I want to meet the person who is dumb enough to steal from their employer and yet clever enough to keep a balance sheet on the amounts of their thefts. Ideally in a public place while I have no cash or credit cards on my person.

posted by winna at 3:06 PM on June 30, 2011

Buckt:

I 'd do something like this:

ways(1 step) = 1 (can only take a single 1-step move)

ways(2 steps) = 2 (can take a 2-step move, or two 1-step moves)

ways(n > 2 steps) = ways(n - 1) (take a 1-step, then recurse through ways of finishing)

+ ways(n - 2) (take a 2-step, then recurse)

+ ways(n - 2) (take two 1-steps, then recurse)

therefore, ways(n > 2 steps) = ways(n - 1) + 2 * ways(n - 2)

you've then got a recursive equation (i think this is correct, but i'm pretty certain the general approach is). It would be nice to be able to find a closed form solution for this (assuming one exists - feels like there is one), but i don't have time for that now.

posted by nml at 3:26 PM on June 30, 2011

*For the one about walking up steps, I can't make it mathy. The options are doing it in n steps, n/2 steps, and everything between n and n/2. How do you math that? Limits? y = lim(n/2 + 1 until n) ?*I 'd do something like this:

ways(1 step) = 1 (can only take a single 1-step move)

ways(2 steps) = 2 (can take a 2-step move, or two 1-step moves)

ways(n > 2 steps) = ways(n - 1) (take a 1-step, then recurse through ways of finishing)

+ ways(n - 2) (take a 2-step, then recurse)

+ ways(n - 2) (take two 1-steps, then recurse)

therefore, ways(n > 2 steps) = ways(n - 1) + 2 * ways(n - 2)

you've then got a recursive equation (i think this is correct, but i'm pretty certain the general approach is). It would be nice to be able to find a closed form solution for this (assuming one exists - feels like there is one), but i don't have time for that now.

posted by nml at 3:26 PM on June 30, 2011

nml, there is a closed form equation for it, but I only know that because it's recognizable as the Fibonacci sequence, and the derivation of that particular equation in a long-ago math class left me blinking with surprise for a long time afterwards.

posted by hattifattener at 4:06 PM on June 30, 2011

posted by hattifattener at 4:06 PM on June 30, 2011

I remember being at university when a bunch of guys had come back from interviews at Goldman Sachs or similar. At first they were discussing "how many pigs are there in China?" and then they moved on to "how much does it cost to put the W in 'George W. Bush'?".

I got hounded out of the room when I pointed out it probably cost more money to put 'Jr.' on the end than it took to put 'W.' in the middle.

posted by edd at 4:08 PM on June 30, 2011

I got hounded out of the room when I pointed out it probably cost more money to put 'Jr.' on the end than it took to put 'W.' in the middle.

posted by edd at 4:08 PM on June 30, 2011

*I got hounded out of the room when I pointed out it probably cost more money to put 'Jr.' on the end than it took to put 'W.' in the middle.*

Of course you did. Did you not know that his dad's name is George H. W. Bush, so that George W. Bush is not a Jr.?

posted by The World Famous at 4:14 PM on June 30, 2011 [1 favorite]

**Jane Street Capital**: What is the smallest number divisible by 225 that consists of all 1’s and 0’s?Wow! My math teacher in school asked our class this exact question in one of those "left as an exercise to the reader" sort of situations. It took me a couple of hours at home to work out that the sum of digits being divisible by 9 is a condition for the number to be divisible by 9. The rest was trivial. But the whole thing left me feeling really dumb for not knowing the divisibility condition. The next day it turned out that I was the only one who had even bothered to work on this at home. Good to know that those hours would have turned useful had I applied for this sort of jobs.

posted by vidur at 4:26 PM on June 30, 2011

I don't know how to sell an invisible pen, but I do know how to sell an invisible ice cream cone.

posted by Daily Alice at 4:36 PM on June 30, 2011

posted by Daily Alice at 4:36 PM on June 30, 2011

The smallest number divisible by n consisting of only 1s and 0s for n = 2, 3, ..., 1999. Via the Encyclopedia of Integer Sequences. For most n I suspect there's no way better than brute force to solve this. 225 is special.

posted by madcaptenor at 4:43 PM on June 30, 2011

posted by madcaptenor at 4:43 PM on June 30, 2011

Fabulous. I'm even

posted by Space Kitty at 5:06 PM on June 30, 2011 [1 favorite]

*less*employable than I feared!posted by Space Kitty at 5:06 PM on June 30, 2011 [1 favorite]

Took me awhile to get to this. 225 = 100 (base 15)

The fact that it is a perfect square begs this to be the correct answer.

posted by dances_with_sneetches at 5:30 PM on June 30, 2011

The fact that it is a perfect square begs this to be the correct answer.

posted by dances_with_sneetches at 5:30 PM on June 30, 2011

Question 1:

Questions 2-9: Are you able to hold conversations and communicate ideas like a more-or-less well-adjusted human being?

Question 10: Do you have any questions?

posted by Riki tiki at 6:21 PM on June 30, 2011 [2 favorites]

*freebie syntax question to make sure you've at least heard of Java.*Questions 2-9: Are you able to hold conversations and communicate ideas like a more-or-less well-adjusted human being?

Question 10: Do you have any questions?

posted by Riki tiki at 6:21 PM on June 30, 2011 [2 favorites]

Ugh. I HATE these kinds of stupid interview questions. They're a waste of my time, a waste of the interviewer's time, and they make the interviewer/company sound like they just read "Interview Questions for Dummies" two minutes before the interview.

I've learned in my relatively short time on this planet that, in business, time is not something to waste and indecisiveness will kill an organization. I don't have time to answer stupid questions like "if you were a tree, what type of tree would you be and why?" just like I don't have time to have 20 status report meetings every week. Ask me about my skills and experience, my goals and my challenges. Don't waste either of our time playing silly interview games because you want to see how creative I am, especially in a non-creative position. These types of questions just seem incredibly unprofessional and amateur to me, and, in my own experience, the people asking these types of questions are the ones interviewing for a minimum or below-poverty wage position in retail or entry-level corporate office positions.

I get just as annoyed at all the cheesy "ice-breaker" games. I don't need to know your life story or you biography or "something unique about you" in order to sit across from you at a conference table or even to work closely with you. If I care (or vice-versa), we'll learn about each other naturally. I know this will get some peoples' backs up or come across snotty but my biggest "pet peeve" about workplaces is all the nonsensical, time-wasting stuff that gets in the way of letting me do my job (or getting a job in the first place). Really, you can't learn that much from people in interviews (other than what they let on, unless they are just really bad interviewees or idiots), and the best way to learn about someone is to get them in the position and see how they perform. So, if you think I'm the best candidate, hire me and see how I do. That's what the probationary period is for.

posted by 1000monkeys at 6:28 PM on June 30, 2011

I've learned in my relatively short time on this planet that, in business, time is not something to waste and indecisiveness will kill an organization. I don't have time to answer stupid questions like "if you were a tree, what type of tree would you be and why?" just like I don't have time to have 20 status report meetings every week. Ask me about my skills and experience, my goals and my challenges. Don't waste either of our time playing silly interview games because you want to see how creative I am, especially in a non-creative position. These types of questions just seem incredibly unprofessional and amateur to me, and, in my own experience, the people asking these types of questions are the ones interviewing for a minimum or below-poverty wage position in retail or entry-level corporate office positions.

I get just as annoyed at all the cheesy "ice-breaker" games. I don't need to know your life story or you biography or "something unique about you" in order to sit across from you at a conference table or even to work closely with you. If I care (or vice-versa), we'll learn about each other naturally. I know this will get some peoples' backs up or come across snotty but my biggest "pet peeve" about workplaces is all the nonsensical, time-wasting stuff that gets in the way of letting me do my job (or getting a job in the first place). Really, you can't learn that much from people in interviews (other than what they let on, unless they are just really bad interviewees or idiots), and the best way to learn about someone is to get them in the position and see how they perform. So, if you think I'm the best candidate, hire me and see how I do. That's what the probationary period is for.

posted by 1000monkeys at 6:28 PM on June 30, 2011

*Question 1:*freebie syntax question to make sure you've at least heard of Java.

Questions 2-9: Are you able to hold conversations and communicate ideas like a more-or-less well-adjusted human being?

Questions 2-9: Are you able to hold conversations and communicate ideas like a more-or-less well-adjusted human being?

I had a job interview somewhat recently at High Tech Company X that was structured more or less like this. One guy gave me a problem to do in Python, which I did, talking through it as I went; it was not very complicated and I assume he just wanted to see how I'd do it, not whether I could. The next guy told me about a problem

*he*had been having in the course of doing his actual job and asked me what I would try, in his position—basically, since I hadn't had any experience with the specific tools involved, a "can you come up with relevant ideas, think about their merits, and communicate them?", which differed from the normal "how many ping pong balls are in my pocket?" kind of question because it pertained to

*an actual problem*, about which the interviewer was knowledgeable because he was

*actually facing it*. And he didn't know the right answer, because it was still a problem for him, so we just talked back and forth about what sorts of things could be done. I'm certain I learned way more in the process than he did; all he could have learned was "this guy can see what general sorts of issue might be relevant to this". It was a surprisingly civilized experience.

A+++ WOULD INTERVIEW AGAIN

posted by kenko at 7:17 PM on June 30, 2011 [5 favorites]

*I get just as annoyed at all the cheesy "ice-breaker" games. I don't need to know your life story or you biography or "something unique about you" in order to sit across from you at a conference table or even to work closely with you.*

They want to know your life story so they can manipulate you or use your personal life in some way to disadvantage you to their benefit.*

Much like any other situation in which you are facing malevolent people who control your destiny, saying as little as possible to give them a hook into your mind is the goal for which you should strive.

*Example: winna doesn't have kids, so she'd be okay to come in on Saturday to do this. None of the rest of us can, because we have children. Sucks to be the one childless person in the office, winn! Lolz!

posted by winna at 7:43 PM on June 30, 2011 [2 favorites]

Amen, sister.

posted by 1000monkeys at 8:18 PM on June 30, 2011

posted by 1000monkeys at 8:18 PM on June 30, 2011

upon further reflection, it looks like i double-counted the 1-step paths in my solution, which means that:

ways(n > 2 steps) = ways(n - 1) + ways(n - 2)

which, as hattifattener pointed out (thanks!), is a slightly-offset fibonnaci sequence.

that feels like a massive understatement, in hindsight.

posted by nml at 10:23 PM on June 30, 2011

ways(n > 2 steps) = ways(n - 1) + ways(n - 2)

which, as hattifattener pointed out (thanks!), is a slightly-offset fibonnaci sequence.

*It would be nice to be able to find a closed form solution for this ..., but i don't have time for that now.*that feels like a massive understatement, in hindsight.

posted by nml at 10:23 PM on June 30, 2011

*What’s the fewest number of times you have to use the scale to find the heavier ball?*

Once, the answer is once. You're trying to find the minimum number of times,

No, you're trying to find the minimum number of weighings that guarantee you have an answer. If I asked you how many times you would have to blind pull a marble out of an urn that has 6 red and 6 blue marbles in it before you got a blue marble, would you answer 1? (Hint: If you did, you'd be wrong.)

Once, the answer is once. You're trying to find the minimum number of times,

No, you're trying to find the minimum number of weighings that guarantee you have an answer. If I asked you how many times you would have to blind pull a marble out of an urn that has 6 red and 6 blue marbles in it before you got a blue marble, would you answer 1? (Hint: If you did, you'd be wrong.)

--kmz

You are changing the question and you changed your question to. The original question says nothing about guarantees, it just says the fewest number. Let's phrase your question similarly:

What's the fewest number of times you would have to blind pull a marble out of an urn with 6 red and 6 blue before you get a blue marble?

The answer is definitely 1.

posted by eye of newt at 11:03 PM on June 30, 2011

"I thought that I wanted to work with your organization. If the execs and upper management are aware of, or worse - encouraged - the criteria for hiring new staff, I must rescind my interest in working with your organization."

posted by porpoise at 11:11 PM on June 30, 2011 [2 favorites]

posted by porpoise at 11:11 PM on June 30, 2011 [2 favorites]

*nml, there is a closed form equation for it, but I only know that because it's recognizable as the Fibonacci sequence, and the derivation of that particular equation in a long-ago math class left me blinking with surprise for a long time afterwards.*

There's a very nice proof of this on page 8 of Generatingfunctionology.

posted by esprit de l'escalier at 2:18 AM on July 1, 2011

*The original question says nothing about guarantees, it just says the fewest number. Let's phrase your question similarly:*

What's the fewest number of times you would have to blind pull a marble out of an urn with 6 red and 6 blue before you get a blue marble?

The answer is definitely 1.

What's the fewest number of times you would have to blind pull a marble out of an urn with 6 red and 6 blue before you get a blue marble?

The answer is definitely 1.

No, the answer's zero, because maybe someone will just show up and hand you a blue marble before you draw any marbles from the urn.

(Come now, that's not how logic problems work.)

*How is the Russian Roulette one different from Monty Haul?*

Misspellings aside, could someone explain how these are different problems? In both:

1) You are (implicitly) randomly assigned to one of several chambers. (ie, you are "assigned" to the chamber after the one the guy spins)

2) The contents of a different chamber are revealed.

3) You are asked whether you now want to switch chambers.

I don't want to give a hyperconfident answer given that it's a topic where hyperconfident answers are often wrong -- but if there's any difference here I can't see it. Anyone?

posted by foursentences at 5:54 AM on July 1, 2011

"I have a message from the Doctor and a question from me. The question: If you could describe Hershey, Godiva and Dove chocolate as people, how would you describe them?"

posted by DevilsAdvocate at 6:24 AM on July 1, 2011

posted by DevilsAdvocate at 6:24 AM on July 1, 2011

*Misspellings aside, could someone explain how these are different problems?*

The difference is that Monty knows which chambers are desirable and which are undesirable, and always chooses to reveal an undesirable chamber. In the Russian Roulette version, a random chamber is revealed.

posted by DevilsAdvocate at 6:29 AM on July 1, 2011 [1 favorite]

Also, if you "switch chambers" (spin again) in the Russian Roulette problem, there is a chance you will get the same chamber which was already revealed (which you know to be a desirable one). In the Monty Hall problem, it is not possible to choose the revealed chamber (not that you would if you could, since it's an undesirable chamber, but you can't anyway.)

posted by DevilsAdvocate at 6:37 AM on July 1, 2011 [1 favorite]

posted by DevilsAdvocate at 6:37 AM on July 1, 2011 [1 favorite]

Procter & Gamble: Sell me an invisible pen.

Sure thing. That'll be googleplex plus 1 dollars. Heck, I'll even throw in a second invisible pen for free.

posted by Human's Nephew at 7:12 AM on July 1, 2011

Sure thing. That'll be googleplex plus 1 dollars. Heck, I'll even throw in a second invisible pen for free.

posted by Human's Nephew at 7:12 AM on July 1, 2011

Devil's Advocate, thanks -- your second post works for me. (The first I don't buy -- the question of whether it's desirable or undesirable would not seem to affect the math, and the question of whether it was revealed by someone knowingly or unknowingly would not seem to matter once it's been revealed.)

posted by foursentences at 8:14 AM on July 1, 2011

posted by foursentences at 8:14 AM on July 1, 2011

*Procter & Gamble: Sell me an invisible pen.*

No - I will

*give*you an invisible pen. It's yours to keep - when you order a box of 100 for your friends and co-workers. But wait! There's more...

posted by anigbrowl at 10:14 AM on July 1, 2011

How is a raven like a writing desk?

posted by Chrysostom at 10:56 AM on July 1, 2011

posted by Chrysostom at 10:56 AM on July 1, 2011

*How is a raven like a writing desk?*

There is a B in both and an N in neither.

posted by The World Famous at 11:02 AM on July 1, 2011 [3 favorites]

*VWR International: How would you market a telescope in 1750 when no one knows about orbits, moons, etc.?*

Well first, I guess I'd wonder where most civilizations got their fucking calendars from. Then I'd ask why the hell am I marketing a telescope when mass production doesn't exist yet. And then I would fold my resumé into a tricorn hat and extolle ye virtues of die Telemetrick Glass in my best sarcastic town crier voice until I was escorted off the premises.

Christ, this almost makes me want to stop ordering from VWR in our lab.

posted by Tikirific at 8:51 PM on July 1, 2011 [2 favorites]

This from the first link made be crack up:

The more I think about it the funnier this line gets and I'm not totally sure why.

posted by en forme de poire at 1:40 AM on July 16, 2011 [1 favorite]

*There’s a typo in your question, there, dude. You said “n,” but I think you were supposed to put a number.*The more I think about it the funnier this line gets and I'm not totally sure why.

posted by en forme de poire at 1:40 AM on July 16, 2011 [1 favorite]

Everyone knows that the only letter which can stand for a number is x.

posted by madcaptenor at 4:36 PM on July 16, 2011

posted by madcaptenor at 4:36 PM on July 16, 2011

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This thread has been archived and is closed to new comments

Pottery Barn: If I was a genie and could give you your dream job, what and where would it beI'm guessing the answer isn't "Not Pottery Barn"

posted by The Whelk at 9:07 AM on June 30, 2011 [18 favorites]