I Did
May 14, 2010 10:32 AM   Subscribe

Terence Tao, former child math prodigy and 2006 Fields Medalist, recently admitted that he only got 4 out of these 5 basic math questions right. Can you do better?

(Quiz is part of this duh story)
(Via)
posted by DU (160 comments total) 10 users marked this as a favorite
 
I got all 5. Go team!
posted by julie_of_the_jungle at 10:35 AM on May 14, 2010


5/5! Where's my Fields Medal?
posted by electroboy at 10:35 AM on May 14, 2010 [5 favorites]


5, and computational math is the area of my brain that putters behind the rest.
posted by Burhanistan at 10:35 AM on May 14, 2010


Yes I can.
posted by craven_morhead at 10:36 AM on May 14, 2010


I spent an inordinate amount of time looking for some trick worked into one of the questions.
posted by ODiV at 10:36 AM on May 14, 2010 [70 favorites]


I fucking kick ass at computing numbers. I got all six of those questions correct.
posted by (Arsenio) Hall and (Warren) Oates at 10:37 AM on May 14, 2010 [76 favorites]


I spent five solid minutes staring the questions down, trying to figure out what the trick was.
posted by decagon at 10:37 AM on May 14, 2010 [3 favorites]


A wise teacher once told me "you lose what you don't use." That's why I've cultivated the habit of doing the math in my head ever since. Makes checkout time go smoother, helps me spot bad deals right away, easier to spot when I'm being overcharged, lets me give exact change etc. One of the best tips I ever received.
posted by Hardcore Poser at 10:37 AM on May 14, 2010 [1 favorite]


5/5 -- I have a third-grader and have to help her with homework every night.
posted by briank at 10:38 AM on May 14, 2010


Yes I can.

So can I.
posted by The Great Big Mulp at 10:38 AM on May 14, 2010


It took me about 2 minutes to get 5/5.


Unlike the 5 out of every 4 people having problems with fractions. ;-)
posted by MikeWarot at 10:38 AM on May 14, 2010


5/5. I was wondering if these were trick questions through the entire ordeal.
posted by Blazecock Pileon at 10:38 AM on May 14, 2010 [11 favorites]


Yeah, perfect too, and I am hardly a math genius. Which one of these do people miss; which one did Tao miss? And why is The Economist asking questions using dollars? (that's suspicious to me.)
posted by Some1 at 10:39 AM on May 14, 2010


But I could have very easily not been paying attention and answered $240 on the last one.
posted by The Great Big Mulp at 10:39 AM on May 14, 2010


I am horrible at math, and i did a 5 of 5 all in my head. and it was really easy.
posted by djduckie at 10:39 AM on May 14, 2010


I looked for a trick too... The only one I could possibly think of getting wrong is the last one. Is that 10 % compounding interest? If not, that would change the answer.
posted by CPAGirl at 10:40 AM on May 14, 2010 [1 favorite]


Which one did he get wrong? Did he just forget about the principle of compound interest?
posted by Burhanistan at 10:40 AM on May 14, 2010


5/5! Where's my Fields Medal?

We only hand those out to people who get 6/5! or more.
posted by Blazecock Pileon at 10:40 AM on May 14, 2010 [1 favorite]


5/5. Of course I read that he got 4 of the 5 questions WRONG so maybe math isn't my problem.
posted by dabug at 10:41 AM on May 14, 2010 [2 favorites]


I think it is a bit sad that a hundred people are about to come into this thread proud of getting those five questions right.

I am assuming Tao just overthought a problem - mapping it to something more complex but not truly isomorphic. That is, he's not dumb, he's just too smart for this.
posted by vacapinta at 10:41 AM on May 14, 2010 [5 favorites]


I am not a math guy, but these are hardly math. It's more like basic logic. I got them all right, but as I was working on them I kept thinking I must be getting set up. Nope.
posted by cccorlew at 10:42 AM on May 14, 2010


Eh, I'm only half happy with my results. The Orcs 2/3 through the 4th level kept tripping me up.
posted by Brandon Blatcher at 10:43 AM on May 14, 2010


As Tao points out, professional mathematicians ≠ calculators. I remember reading in Enigma (which is great) that Alan Turing was not allowed to keep the bridge score.
posted by Jorus at 10:43 AM on May 14, 2010 [2 favorites]


The last question wasn't correctly specified either. It should include something like "...assuming that all interest is added to the savings account..." otherwise its less a math question than one about default banking practices.
posted by vacapinta at 10:44 AM on May 14, 2010 [10 favorites]


Here's a fun question to try to do quickly in your head. Three faucets can fill up a tub - red, blue, and green. Acting alone, the red faucet can fill up the tub in 20 minutes, the blue faucet can fill up the tub in 40 minutes, and the green faucet can fill up the tub in an hour. If all three faucets are turned on at the same time to fill up the tub, what fraction of the water in the tub would be filled by water coming out of the green faucet?
posted by (Arsenio) Hall and (Warren) Oates at 10:44 AM on May 14, 2010


5/5 and I hate the math...
posted by stenseng at 10:44 AM on May 14, 2010


Hey, I am a prodigy, just like Dad said!

Dad was a mathematician. He was thrilled to learn that his tiny daughter "just knew" the solutions to the algebra problems he was teaching The Big Kids, and that I lulled myself to sleep at night by counting the differentials between square numbers. Sadly, that was the end of my mathematical career: no prodigy, just a passing freak interest, like all kids have in various subjects.

Yeeeah, knowing that an actual prodigy had trouble with one of the questions gives a heads-up to pay attention to the only remotely tricky problem there. (And by "remotely tricky," I mean "requires two simple arithmetic operations, not one.")
posted by Elsa at 10:45 AM on May 14, 2010


I got all 5 - was it the compound interest that tripped him up?
posted by Dasein at 10:45 AM on May 14, 2010


That is, he's not dumb, he's just too smart for this.

I'm not saying he is dumb by any stretch, but it's a bit of a dangerous presumption to call someone "too smart" for anything.
posted by Burhanistan at 10:46 AM on May 14, 2010 [1 favorite]


"If all three faucets are turned on at the same time to fill up the tub, what fraction of the water in the tub would be filled by water coming out of the green faucet?"

two weasels with a remainder of one
posted by HuronBob at 10:46 AM on May 14, 2010 [2 favorites]


I don't think Tao said which one he got wrong.

It should include something like "...assuming that all interest is added to the savings account..." otherwise its less a math question than one about default banking practices.

I thought the same thing until I realized the interest was 10%. Definitely not a real banking practices question.
posted by DU at 10:46 AM on May 14, 2010 [5 favorites]


5/5, also suspecting that there was some trickery involved and surprised to find that there was not.
posted by jquinby at 10:47 AM on May 14, 2010


I don't get it -- there's no place to enter the parameters of the proper binomial distribution for the second answer.
posted by gurple at 10:47 AM on May 14, 2010 [1 favorite]


Which one of these do people miss; which one did Tao miss?

I'm guessing (hoping?) it's the interest one, which is the only one that's remotely tricky (some people may forget to include the first year's interest in calculating the second).

That said, a surprising amount of people just can't do arithmetic. I saw someone reach for a calculator to figure $1.35 x 10 the other day -- I had a visceral sense of what is wrong with you ten portobello mushrooms are $13.50 arrrrgh!
posted by vorfeed at 10:47 AM on May 14, 2010


Two-elevenths?
posted by adipocere at 10:48 AM on May 14, 2010 [2 favorites]


That was easy - I was certain that they would be trick questions somehow, but no...5/5!
posted by newfers at 10:49 AM on May 14, 2010


4/5 -- rushing through and not really thinking about how compound interest works. D'oh! And yes, I was also incredibly paranoid about phrasing and trickery.
posted by Shepherd at 10:49 AM on May 14, 2010 [1 favorite]


The trick question is number five: where are you going to find a savings account that generates 10% annual return?
posted by tomierna at 10:50 AM on May 14, 2010 [4 favorites]


5/5. And I barely passed remedial algebra.
I'm guessing the problem that trips most people up is the bank interest question. Most folks, I suspect, forget to compound the interest.

And, who do I have to be killed by to get 10% on my savings?
posted by Thorzdad at 10:50 AM on May 14, 2010 [2 favorites]


We only hand those out to people who get 6/5! or more.

Dude, a 5% correct answer rate gets you a Fields Medal?

Though, I suppose if the 6 you got out of 120 were all Hilbert Problems...
posted by kmz at 10:51 AM on May 14, 2010


damn. forgot to compound the interest. stupid, stupid, stupid! (smacks self in forehead repeatedly...)
posted by saulgoodman at 10:52 AM on May 14, 2010


Yep!
posted by (Arsenio) Hall and (Warren) Oates at 10:53 AM on May 14, 2010


I got them all, and thought they were fairly easy. I still don't understand calculus, however.
posted by infinitywaltz at 10:53 AM on May 14, 2010


Although the questions are pretty straightforward, I wouldn't be surprised if Tao just misread one. I know I tend to misread questions like these more often than I'd like.
posted by Ceniac at 10:54 AM on May 14, 2010


This thread is annoying. Of course we all got 5/5. We slowed down enough to take the questions seriously (and slower yet, to look for "tricks").

Ha, professional musician! You hit a wrong note! Watch me play your piano piece at a tenth of the pace and make not one mistake!

This should be a Facebook application. It's that pointless and feel-good.

Yes, I'm feeling curmudgeonly today. Thanks for asking.
posted by Durn Bronzefist at 10:54 AM on May 14, 2010 [10 favorites]


oh dear, the Blue is smarter than Tao

You scored 5 out of 5

What your score means
0-1 Oh dear: Mr Madoff would love to meet you some day
2-3 Not great: Best steer clear of the synthetic derivatives market
4 Not bad: On a par with Goldman Sachs's institutional clients
5 Perfect: We're seeking a new finance director. Care to apply?
posted by infini at 10:55 AM on May 14, 2010


slow?? it didn't take a couple of minutes...
posted by infini at 10:56 AM on May 14, 2010


If you let the three faucets run for 2 hours, you would have 6 tubs from the red faucet, 3 tubs from the blue faucet and 2 tubs from the green faucet.

6 + 3 + 2 = 11.

2/11 is the amount of water that would be from the green faucet.

So even if you just ran the faucets long enough to fill the tub once, the proportions would be the same.

2/11 of the water would be from the green faucet.
posted by marsha56 at 10:56 AM on May 14, 2010 [1 favorite]


The trick question is number five: where are you going to find a savings account that generates 10% annual return?

Answering the last question correctly, given its highly suspect claims about rates of returns on savings, adds you to a list of potential future targets for Madoff-style investment scams, therefore, those of us who forgot to compound the interest are vindicated by our own innumeracy.
posted by saulgoodman at 10:56 AM on May 14, 2010


Got 'em all wrong. I must be some kind of superman!!!
posted by tigrefacile at 10:57 AM on May 14, 2010 [1 favorite]


how is 6,000 2/3rds of 9,999?
posted by empath at 10:57 AM on May 14, 2010


what is wrong with you ten portobello mushrooms are $13.50 arrrrgh!

Oh now don't you start that again.
posted by shakespeherian at 10:58 AM on May 14, 2010


I liked the article. I wish math didn't scare so many people -- when you learn how to use it in your everyday life, it only gets easier and the payoffs are immediate.

I've taught a few boyfriends and roommates how to figure out the best price between different brands and sizes at the grocery store by dividing the price by the number of ounces. We've avoided so many bogus sales that way. (Never assume that bulk means better value. Grocery stores pull that trick all the time.)
posted by Toothless Willy at 10:58 AM on May 14, 2010


it isn't, Teh economist was pulling your leg, empath. I picked 9000 and got 5/5 unless you're pulling my leg, in which case I want my bucket, what faucets?
posted by infini at 10:58 AM on May 14, 2010


how is 6,000 2/3rds of 9,999?

oh, nm, i'm stupid, i clicked 9,999 instead of 9,000... yay for not looking closesly.
posted by empath at 10:59 AM on May 14, 2010


toothless willy , yup, supermarket pricing is fixed and it wuz mom who taught me all this number jiggery pokery while shopping
posted by infini at 10:59 AM on May 14, 2010


Punch the Monkey
posted by pracowity at 11:00 AM on May 14, 2010


What your score means
--> 5 Perfect: We're seeking a new finance director. Care to apply?

posted by grubi at 11:00 AM on May 14, 2010


I've taught a few boyfriends and roommates how to figure out the best price between different brands and sizes at the grocery store by dividing the price by the number of ounces.

At my grocery store the tag lists the price per ounce.
posted by shakespeherian at 11:01 AM on May 14, 2010 [6 favorites]


I had to actually write out the progression on No. 5, because I'm pathologically unable to do simple math in my head. But I got 5 out of 5. WHERE'S MY BONUS, FUCKERS?
posted by Cool Papa Bell at 11:02 AM on May 14, 2010


I got all five, and count me as one of the people who spent too much time looking for tricky questions.
posted by sfred at 11:02 AM on May 14, 2010


Nthing the compound interest. 4/5
posted by brundlefly at 11:02 AM on May 14, 2010


I like this thread, its "flash friday" with a twist. thanks DU
posted by infini at 11:03 AM on May 14, 2010


Ok you tubthumpers, here's one for you:

You have fifteen circular tubs (radius = 1.3m, depth = 1/3m) are randomly distributed on a 14*14m plane. Hot sauce is falling at a steady rate of 1.3L/m^2/min at the center of the plane, but tapers linearly to zero at radius=14 meters. What is the probability that any single hot sauce container will be full after 3 hours?

PS. I don't know the answer.
posted by The White Hat at 11:06 AM on May 14, 2010


Arithmetic is just a very, very tiny part of math.
posted by chimaera at 11:06 AM on May 14, 2010 [1 favorite]


It's easy to get 5/5 if you simply pay attention and take your time. If you're trying to do it too fast it's also easy to screw a couple of these up.

BUT 5/5 HELL YEAH
posted by GuyZero at 11:08 AM on May 14, 2010


Ok you tubthumpers, here's one for you [...] What is the probability that any single hot sauce container will be full after 3 hours?

Zero, because the circular tubs can't possibly cover the entire plane without gaps, which means a great deal of hot sauce isn't collected at all and goes all over the floor. Even a perfectly-positioned tub won't be full before the plant manager shuts the damn thing off.
posted by FishBike at 11:12 AM on May 14, 2010 [4 favorites]


A few things are at work here:

1. everyone clicking the link and doing the problems are taking their time and being extra careful to avoid any misreadings,

so yeah everyone is getting 5/5, and if you don't under this set-up you are in trouble.

2. (assumption) Tao, breezed though them and misread/got a line crossed and chose a wrong answer in haste.

3. Number 2 happens all the time, to most of us. Hell, you see it on Metafilter every single day, where so and so starts yammering on about how such an article doesn't address a given VERY IMPORTANT ISSUE!!!, when all they did was miss a sentence or paragraph. And yet, we don't accuse them to being bad at English, or some sucklike (ok this is metafilter, I'm guessing someone actual does make that accusation

4. Frankly Tao should be patted on the back for so publicly admitting making such an error

5. Finally, I encourage people to cease with the 5/5.
posted by edgeways at 11:12 AM on May 14, 2010 [1 favorite]


Not bad: On a par with Goldman Sachs's institutional clients

But not a winning stroke for The Economist's editors.
posted by Smart Dalek at 11:13 AM on May 14, 2010


Shouldn't the last question have specified simple or compound interest? (I got it right anyway, but still.) Also: Math Class Needs a Makeover
posted by effwerd at 11:14 AM on May 14, 2010 [2 favorites]


Metafilter: Number 2 happens all the time, to most of us.
posted by gurple at 11:14 AM on May 14, 2010


I don't feel especially smart for getting these questions right.

Now, if I can find a savings account where I get 10% interest I'll be psyched.

Assuming that's not in some future with 12% inflation, of course.
posted by yohko at 11:15 AM on May 14, 2010


At my grocery store the tag lists the price per ounce.

At my grocery store, the tag for one box lists price per ounce. The tag for the otherwise-identical box of a different brand lists price per pound. And the tag for the third brand lists "per item." They're never helpful.
posted by not that girl at 11:17 AM on May 14, 2010 [3 favorites]


Used to be fashionable for mathematicians to disdain computation and claim ineptitude in arithmetic.

Ulam, for example (in paraphrase):'You won't believe how far I've sunk-- my last paper had numbers with decimal points in them.'

Always tempting to remind such people that Gauss was a lightning calculator (not to mention Euler), though this would have been terribly unfair to Ulam.
posted by jamjam at 11:18 AM on May 14, 2010


Show me a bank account that only compounds once at the end of every year.
posted by Nelson at 11:22 AM on May 14, 2010 [3 favorites]


For an excellent example of professional mathematicians getting tripped up by actual numbers, you can't do much better than Alexander Grothendieck (PDF), one of the foremost mathematicians of the 20th century. Grothendieck was well-known for thinking about mathematics in very general terms, without reference to specific examples. When pressed for specific examples, he didn't always do as well:
One striking characteristic of Grothendieck’s mode of thinking is that it seemed to rely so little on examples. This can be seen in the legend of the so-called “Grothendieck prime”. In a mathematical conversation, someone suggested to Grothendieck that they should consider a particular prime number. “You mean an actual number?” Grothendieck asked. The other person replied, yes, an actual prime number. Grothendieck suggested, “All right, take 57.”
posted by Johnny Assay at 11:24 AM on May 14, 2010 [3 favorites]


I got 5/5, but my wife's a math person, so it was probably learning through cuddling/osmosis.
posted by SNWidget at 11:24 AM on May 14, 2010 [1 favorite]


At my grocery store, the tag for one box lists price per ounce. The tag for the otherwise-identical box of a different brand lists price per pound. And the tag for the third brand lists "per item." They're never helpful.

Yick. I guess all I have to offer is that I could buy your groceries and mail them to you.
posted by shakespeherian at 11:25 AM on May 14, 2010


what is wrong with you ten portobello mushrooms are $13.50 arrrrgh!

Oh now don't you start that again.

--shakespearian

At least the cashier knew what the mushrooms were.
posted by Drexen at 11:26 AM on May 14, 2010 [1 favorite]


Not bad: On a par with Goldman Sachs's institutional clients

But not a winning stroke for The Economist's editors.


Smart Dalek, that use is explicitly approved in The Economist Style Guide.
posted by Jorus at 11:26 AM on May 14, 2010


I got all 5. However, I had to figure out number 5 by process of elimination - for some reason my brain stalled at figuring out 10% of 220.
posted by nooneyouknow at 11:27 AM on May 14, 2010


oh, nm, i'm stupid, i clicked 9,999 instead of 9,000... yay for not looking closesly.

You fool! Your answer was OVER NINE THOUSAND!!!!!
posted by Faint of Butt at 11:28 AM on May 14, 2010


5. Jeebus. How could you get any of these wrong?
posted by unSane at 11:36 AM on May 14, 2010


Surprised no one's mentioned, but -- not only were these easy questions, they were made much easier by being presented as a multiple-choice test, where two or three choices for each question were glaringly obviously wrong. Sheesh.
posted by webmutant at 11:37 AM on May 14, 2010


oh dear, the Blue is smarter than Tao

The Tao of Blue?
posted by Confess, Fletch at 11:38 AM on May 14, 2010 [1 favorite]


5. Finally, I encourage people to cease with the 5/5.

It's ok, 4/5 is still a perfectly respectable score. I'm sure you have other good qualities.
posted by electroboy at 11:44 AM on May 14, 2010


1. Obviously the couch costs less than 150 or rational actor theory says the store wouldn't have the sale. It also fits in with other psychological factors to have a massive discount "sale;" if you've ever researched buying a car you know the sticker price is fake anyways. So the only choice is that the couch costs the retailer $120.

2. Gurple's already addressed this one.

3. Same concept as question 1. So (dealer invoice) - (incentives) is probably around $8000.

4. Statistically speaking, Everyone takes the lump sum instead of the 20 year annuity, so the payout is going to be smaller than the 2 million pot. If you figure a generous 7 percent interest rate for the time discount they'll each get roughly 100k.

5. $240, 20 dollars in interest the first year, 22 the second, and 1 dollar a year in fees because my bank charges me 10 cents per debit transaction. I try to use my Discovercard to avoid that but the local sub shop doesn't accept them.
posted by pwnguin at 11:44 AM on May 14, 2010 [5 favorites]


The Tao of Blue?

the title of #1's next book?
posted by infini at 11:55 AM on May 14, 2010


5/5, but I really do use arithmetic (and algebra and geometry, but nothing else) on a daily basis way more than I ever expected to as a kid.
posted by padraigin at 11:58 AM on May 14, 2010


5/5, but wondered what I was missing right up until I hit the results button.
posted by kinnakeet at 11:59 AM on May 14, 2010


5/5

I iz genius.
posted by Hairy Lobster at 12:00 PM on May 14, 2010


At my grocery store the tag lists the price per ounce.

I believe that's by law in the US. Which is Yet Another Thing WalMart Creatively Complies With. They often list unit prices in different units for competing brands, rendering the disclosure moot.
posted by DU at 12:00 PM on May 14, 2010


10% on a measly deposit of $200? I smell a Ponzi scheme.
posted by yeti at 12:00 PM on May 14, 2010


BTW these questions were fine. But to this day if anyone starts talking trigonometry--the mere mention of sine, cosine, tangent etc.--I break a full body sweat.
posted by kinnakeet at 12:01 PM on May 14, 2010 [2 favorites]


5/5, but I read grades 2-12 test questions all day long, so I'm used to reading these sorts of things very carefully and working a lot of elementary math.

I also failed algebra three times (then got a mercy D, which allowed me to fail pre-calculus).
posted by fiercecupcake at 12:02 PM on May 14, 2010


Almost a hundred comments and nobody pointed out this "prodigy" uses Google Buzz?
posted by mek at 12:02 PM on May 14, 2010


My bad on the grammar portion; here's my work for The White Hat:

You have fifteen circular tubs (radius = 1.3m, depth = 1/3m) are randomly distributed on a 14*14m plane. Hot sauce is falling at a steady rate of 1.3L/m^2/min at the center of the plane, but tapers linearly to zero at radius=14 meters. What is the probability that any single hot sauce container will be full after 3 hours?

Given that the average pepper used in uncooked form within salads contains ~0-100 Scoville worth of capsicum, and peppers employed in the preparation of hot sauces commonly fall in the range of 1000+ Scoville (as with cubanelle, jalapeño and Hungarian wax varieties), the likelyhood of any single container being full within 3 hours is exactly 100%. It should be noted that the fullness of the container is dependent upon two distinct variables:


a) the final packaging of hot sauce for distribution

b) the resale value (rv) of the hot sauce itself [rv= anticipated consumer demand of hot sauce (estimated distributor interest and sustained demand for restock of product) / size and availability of final packaging for hot sauce container - (overhead costs for production, printing, trademark registry + distribution and up-front costs of initial promotion of final product) + applicable sales tax under condition of any artificially-produced emulsifiers being added to the hot sauce to sustain shelf life of the product, as well as any possibility of artificial colors being added to enhance the visual appeal of the hot sauce itself].



As the size of the end product and its particular labeling and trademarked name can afford an assumption of desirable exclusivity toward associating with the product, the overhead of the rv can be increased, so long as it does not disrupt the mean proportion of distribution and sustainable promotion of the hot sauce, nor detract from consumer interest through excessive promotion nor final sale expenses. Given this scale, any percentage of capsicum that can be mixed with water for at least satisfying a Scoville ratio proportional to a mild rating or greater can be considered nominal for satisfying the initial end-product requirement of providing proof-of-concept valuation for (potentially) incurring distributor interest toward committed supply of stock space for resale to consumers.
posted by Smart Dalek at 12:03 PM on May 14, 2010 [1 favorite]


The White Hat: "Ok you tubthumpers, here's one for you:

You have fifteen circular tubs (radius = 1.3m, depth = 1/3m) are randomly distributed on a 14*14m plane. Hot sauce is falling at a steady rate of 1.3L/m^2/min at the center of the plane, but tapers linearly to zero at radius=14 meters. What is the probability that any single hot sauce container will be full after 3 hours?
"

What do you mean, African or European hot sauce?
posted by xedrik at 12:04 PM on May 14, 2010 [1 favorite]


I got 6/5. Go numeracy!
posted by zippy at 12:06 PM on May 14, 2010


What is the probability that any single hot sauce container will be full after 3 hours?

Are Oprah, John Goodman or Mario Batali anywhere nearby?

Get it? Because they like to eat ... ?
posted by Cool Papa Bell at 12:08 PM on May 14, 2010


Math people I know usually claim to be bad at arithmetic. This is generally not true. However, it is often true that they are just okay at arithmetic and prefer not to do it.
posted by grobstein at 12:23 PM on May 14, 2010 [1 favorite]


I'm a sale shopper so I did these quite easily. I'm puzzled though, are the math geeks just looking at it too closely? Thinking too hard about it?

Like, 10% on a savings account? Compounding how often...?
posted by Ruthless Bunny at 12:29 PM on May 14, 2010 [1 favorite]


Everyone I know who studied pure math with me at University couldn't calculate a tip or split a bill or do all sorts of simple things. They were also so fucking smart, so I guess that wasn't the end of the world.
posted by chunking express at 12:30 PM on May 14, 2010


Also, I didn't divide 2 million by 5 properly, so I got 4/5 right. God damn it. I think if you just quickly looked at the questions and whipped through them you could end up making an equally silly mistakes. I seriously doubt he was 'overthinking' the problems. It's more likely he didn't read a number correctly, like me.
posted by chunking express at 12:32 PM on May 14, 2010 [1 favorite]


Basically, then, this is a test of mathematical numeracy and whether people guess whether the last question assumes simple or compound interest. A little misleading.

Given the (lack of) difficulty or nuance to the questions at all until the compound interest one, one might almost think it was written on purpose this way. As in, to compile data that the American public is worse at math than they really are.
posted by JHarris at 12:37 PM on May 14, 2010


5/5. But I bet I still suck at math. :)
posted by zarq at 12:37 PM on May 14, 2010


At my grocery store the tag lists the price per ounce.
posted by shakespeherian


Yes, that is handy when it's available, isn't it?
posted by Toothless Willy at 12:40 PM on May 14, 2010


Awwwwww jeaaah! Now on to part two.
posted by spikeleemajortomdickandharryconnickjrmints at 12:41 PM on May 14, 2010


Like, 10% on a savings account? Compounding how often...?

My understanding is that when interest is cited as an annual percentage, the compounding frequency doesn't matter. That's because the actual interest rate used for each interest payment is calculated to result in exactly 10% interest after 1 year taking into account the action of compound interest.

So for example with monthly compounding, the interest rate used to get 10% APR isn't (0.1 / 12) = 0.833% as you might expect. Instead it's (1.1(1/12)-1)=0.797% per month. Compounded over 12 months, that gives you the same amount of interest as a 10% lump sum once a year.
posted by FishBike at 12:49 PM on May 14, 2010 [1 favorite]


The various methods of compound interest are kind of moot, though. The question simply states "The account earns ten per cent interest per year". The question logically gives you all you need to solve the problem correctly with that statement.
posted by Burhanistan at 12:53 PM on May 14, 2010 [1 favorite]


5/5 while talking on the phone to my wife (I hope she doesn't read this) but then I am not a mathematician and I can't do all the stuff that they do with its surprising lack of numbers etc.
posted by caddis at 1:04 PM on May 14, 2010


Exactly. The last question isn't a trick question.
posted by chunking express at 1:05 PM on May 14, 2010


5/5, but I really do use arithmetic (and algebra and geometry, but nothing else) on a daily basis way more than I ever expected to as a kid.

Algebra? Really?

I'm no mathematician (as evidenced by my 0/5 score) and I do use arithmetic and simple geometry more often in daily life than I thought I would, but I only ever use a kind of faux algebra when I'm trying to be unpleasant about someone but with a degree of deniability in case one of my colleagues is wearing a wire.

"You know X? X is a vile c**t. And possibly a thief. How do I know? Y told me. Those were her exact words."
posted by tigrefacile at 1:07 PM on May 14, 2010 [1 favorite]


I got all 5 right. Whenever my husband and I go out, I always calculate the tip faster. Sometimes I give him crap about it because he was a math major (mostly for the comp sci concentration) and he always says "I'm not good at arithmetic."

I'm not mathy but sometimes I wonder how mathematicians see the world. I imagine it'd be quite alien. Then again, I imagine physics majors see the world like a video game.
posted by zix at 1:11 PM on May 14, 2010 [1 favorite]


People say things like "math is the universal language" and "with a clever enough equation, you can understand how it all works".

I hate those people. Because my relationship with math is a lot like that between a dog and a vacuum. One side is completely indifferent where the other is totally filled with terror and confusion whenever they meet.

Nevertheless 5/5.
posted by quin at 1:14 PM on May 14, 2010 [16 favorites]


5 of 5, despite being an English professor.
posted by thomas j wise at 1:18 PM on May 14, 2010


Really? People miss some of these questions?

Well, I guess it's good that the Republicans are trying to kill that dastardly bill to give more money to science and math education...
posted by Mental Wimp at 1:29 PM on May 14, 2010


X is a vile c**t
Wow, I haven't seen that notation in ages. You know, you can use the <sup> tag in the comment box here.
posted by hattifattener at 1:37 PM on May 14, 2010 [5 favorites]


Once you learn FORTRAN, it's hard to do otherwise.
posted by GuyZero at 1:44 PM on May 14, 2010


5. Jeebus. How could you get any of these wrong?

In my case, rushed through and just completely forgot to compound the interest on the last one. Dumb, I know, but then, in real life, interest is typically amortized and compounded quarterly, so the answer, without rounding to the nearest cent, really should have been more like:

$243.68(0579501983642578125)

Or, broken down by quarter:

Year 1
1 - 205.00
2 - 210.12(5)
3 - 215.37(8125)
4 - 220.76(2578125)

Year 2
1 - 226.28(1642578125)
2 - 231.93(8683642578125)
3 - 237.73(7150733642578125)
4 - 243.68(0579501983642578125)

If your bank only pays out $242.00 at 10% interest, you're getting ripped off.
posted by saulgoodman at 1:50 PM on May 14, 2010 [1 favorite]


The question logically gives you all you need to solve the problem correctly with that statement.

Says you. ;)
posted by saulgoodman at 1:51 PM on May 14, 2010


Are we really this bad at math??? Sweet Jesus...
posted by LordSludge at 1:56 PM on May 14, 2010


5/5, and these were really easy. I think Tao must have just overthought his plate of numerical beans. But then, I'm great at doing arithmetic in my head and just suck rocks when it comes to algebra and trigonometry and calculus.

This is where I get to brag on my husband, who got a perfect score on the math portion of his SAT back in the day, right? Right? SAT scores have to be good for something!
posted by misha at 1:58 PM on May 14, 2010 [1 favorite]


All of you guys that are proud of the 5/5 are secretly wondering if this confirms that you're a genius. You're not. They are just trying to make you feel better and get more clicks. Haha.
posted by anniecat at 2:09 PM on May 14, 2010


They could have paid Tao a nice sum of money to say he got one wrong on purpose.

I bet you all do really well on the IQ test that comes up as a pop-up. It's pretty obvious that this is a joke.
posted by anniecat at 2:10 PM on May 14, 2010


A wise teacher once told me "you lose what you don't use." That's why I've cultivated the habit of doing the math in my head ever since. Makes checkout time go smoother, helps me spot bad deals right away, easier to spot when I'm being overcharged, lets me give exact change etc. One of the best tips I ever received.

I bought a calculator.
posted by inigo2 at 2:10 PM on May 14, 2010


saulgoodman: "5. Jeebus. How could you get any of these wrong?

In my case, rushed through and just completely forgot to compound the interest on the last one. Dumb, I know, but then, in real life, interest is typically amortized and compounded quarterly, so the answer, without rounding to the nearest cent, really should have been more like:

$243.68(0579501983642578125)

Or, broken down by quarter:

Year 1
1 - 205.00
2 - 210.12(5)
3 - 215.37(8125)
4 - 220.76(2578125)...
"

See this comment.
posted by alexei at 2:19 PM on May 14, 2010


FishBike: "Ok you tubthumpers, here's one for you [...] What is the probability that any single hot sauce container will be full after 3 hours?

Zero, because the circular tubs can't possibly cover the entire plane without gaps, which means a great deal of hot sauce isn't collected at all and goes all over the floor. Even a perfectly-positioned tub won't be full before the plant manager shuts the damn thing off.
"

It seems you stumbled onto the correct answer to the original question: even at the center of the plane, the rate is only 1.3L/m^2/min = 1.3 mm/min, which means that after 3 hours the tub would only be full to 234 mm, or less than the 333 mm height of the tub. Zero chance of filling any tubs.
posted by alexei at 2:28 PM on May 14, 2010 [1 favorite]


I'm betting he screwed up the last one - 10 percent a year interest - because they didn't state when the interest was compounded. A math whiz might assume something other than annually ....
posted by Twang at 2:31 PM on May 14, 2010 [1 favorite]


5/5 hell yeah! Do you hear that, [every math teacher that I had up through high school], damn your black hearts?
posted by Halloween Jack at 2:31 PM on May 14, 2010


Okay, the hot sauce one? The answer is 0, because the tubs are freaking huge.

Say you take one of the tubs, with its radius of 1.3 m and depth of 1/3 m. That's a total volume of pi*(1.3)^2*(1/3) = 1.76976 m^3 = 1769.76 L.

If we take the maximum rate of 1.3 L/m^2-min and multiply by the surface area of pi*(1.3)^2 = 5.309 m^2 we get 6.902 L/min for a single tub. Note that that's more than the maximum possible because the rate of hot sauce deposition tapers off linearly from the center.

If we multiply the 6.902 L/min by the total time in minutes (3 hrs = 3*60 = 180 min), we get the maximum amount of sauce deposited. Which is 6.902*180 = 1242.36 L. Which is still less than our tub volume of 1769.76 L.

If a tub being filled at the maximum possible rate over its entire area can't be filled in 3 hours, no tub has a chance of being filled at all. So it's 0.

Yeah, I didn't use the proper number of significant figures in my calculation, I know.
posted by malthas at 2:42 PM on May 14, 2010


And alexei beat me to it and did it in a much simpler manner.
posted by malthas at 2:43 PM on May 14, 2010


Damn, beat to the answer. Silly me, starting out trying to deal with the problem in a general way. Let's just say it involved polar coordinates and the integral of an inverse cosine.
posted by valrus at 4:01 PM on May 14, 2010


But I could have very easily not been paying attention and answered $240 on the last one.

I was paying close attention and did answer $240. I assumed no compounded.

My understanding is that when interest is cited as an annual percentage, the compounding frequency doesn't matter.

But that's still assuming that there is a compounding frequency, right? Couldn't there also be a total lack of compounding?

/my .01% of $200.
posted by mrgrimm at 4:01 PM on May 14, 2010


*no compounded interest
posted by mrgrimm at 4:02 PM on May 14, 2010


This would make an interesting meta-test. Almost all of us suspected trick questions and wasted time rechecking our answers. But the better you are at this sort of stuff, the more confident you should be that your straight-forward answers are right and you haven't been tricked. So the interesting test would be if they timed how quickly you finished, assuming you got all 5 right, suspected trick questions, and didn't know you were being timed. Without the fear of tricks, most could probably answer them all in under a minute. The longer you take, I'd imagine the less likely you are to be able to answer considerably harder questions (statistically speaking, anyway; I'm sure there's a lot of individual variability in the match between self-confidence and ability).
posted by chortly at 4:23 PM on May 14, 2010 [1 favorite]


Ha, it reminded me of the numeracy test I took in order to work as a Life Ruination Consultant* at a payday loan place. Sounds like Terence Tao isn't going to be slinging high-interest loans for $8/hour anytime soon!

*clerk
posted by maus at 5:10 PM on May 14, 2010


Here's a fun question to do in your head.
posted by Sparx at 6:28 PM on May 14, 2010


Hmm, must be test day, I just got hit with this one over on Reddit. 129, calculated using the standard deviation 16. I wish it told me which ones I got wrong.
posted by Purposeful Grimace at 7:47 PM on May 14, 2010


It's kinda funny, I'm almost 30 years old and usually quite good with math, but it wasn't until earlier this year I grasped that division could conceptually mean two things.

I always looked at division as "How big is one piece when you divide X into Y pieces", but the additional meaning of "How many pieces do you get if you divide X into pieces of size Y" had completely eluded me for some reason. And I've been juggling variables enough in equations that the concept should be obvious to me. Everyone has small holes in their knowledge, and I guess this test hit one of Tao's. (Assuming it wasn't just a miscalculation or wrong pick)

(I got 5 out of 5, but yeah, spent a bit of time looking for some trick too.)
posted by ymgve at 7:50 PM on May 14, 2010


A master arc welder should still be able to read the instructions on a pack of matches.
posted by Burhanistan at 7:56 PM on May 14, 2010


Maybe, but not because they are a master arc welder(?).
posted by grobstein at 9:33 PM on May 14, 2010


those of us who forgot to compound the interest are vindicated by our own innumeracy.

I didn't forget compound interest. I just thought, since the first questions were so simple, that if they had meant compound interest they would have said so. =/

4/5

Back to schools with me.
posted by Kutsuwamushi at 9:42 PM on May 14, 2010


Sure, those questions were easy. But can you answer these?

1) A bat and a ball cost $1.10 in total. The bat costs $1 more than the ball. How much does the ball cost?
2) If it takes five machines 5 minutes to make five widgets, how long would it take 100 machines to make 100 widgets?
3) In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half of it?

Supposedly, when researchers put the following three problems to 3400 students in the US, only 17 per cent got all three right.
posted by twoleftfeet at 11:19 PM on May 14, 2010


1. ten cents
2. 5 minutes
3. 47 days

btw, chortly's point:

The longer you take, I'd imagine the less likely you are to be able to answer considerably harder questions (statistically speaking, anyway;

is kind of the roots of the GMAT scoring style on computer based tests. (I don't know the latest GRE testing style) You get the first 5 or 7 questions right (take your time) and it pops your score in the highest bracket, after which every wrong answer brings it down a little bit.

To compute the scaled score for each section, GMAC uses an algorithm that takes into account the following factors:

* the number of questions answered within the time permitted
* the number of questions answered correctly
* the statistical characteristics (including level of difficulty) of the questions answered

At the beginning of each section the computer presents a question in the middle range of difficulty. If the question is answered correctly, the next question will be harder, and the score will adjust upwards. If the question is answered incorrectly, the next question will be easier, and the score will adjust downwards. (The test taker does not see this adjustment, however, because the score is not revealed until the entire test has been completed.) Thus, the computer is constantly recalculating the scaled score as the student progresses through the section.

The more questions that are answered, the more familiar the computer becomes with the skills of the test taker and consequently, the more certain the computer is of the scaled score it has calculated. Hence, the questions at the beginning of the section count much more than do the questions at the end of the section. For example, by the time Question 36 appears, the computer has had 35 questions' worth of information from which to derive the proper score range. So even if Question 36 were answered correctly, the increase in score would be minimal compared to the increase in score if Question 2 had been answered correctly.

posted by infini at 11:39 PM on May 14, 2010


infini: 1. five cents.
posted by ODiV at 11:42 PM on May 14, 2010


explain how, I didn't get it
posted by infini at 11:46 PM on May 14, 2010


*duh* :)

serves me right
posted by infini at 11:50 PM on May 14, 2010 [1 favorite]


If there are ten fingers on two hands, how many fingers are there on ten hands?

A lot of people say one hundred.
posted by twoleftfeet at 4:53 AM on May 15, 2010 [1 favorite]


If there are ten fingers on two hands, how many fingers are there on ten hands?

Your question has been rated: AMBIGUOUS. Thank you for submitting to the Metafilter Ambiguity Tester!
posted by Mental Wimp at 6:00 AM on May 15, 2010


5 cents, 5 minutes, 1 day.
posted by empath at 10:47 AM on May 15, 2010


The last question twoleftfeet asked is about 46.7 days if I've done the math correctly; lilypads are round, not hexagonal, so there would have to be overlap for them cover the entire lake.

This of course does not take into account that the lilypads would be of varying sizes or the effects of the border of the lake, nor daily or seasonal changes in the water level.

A lot of the original questions, too, also would have a few more considerations (taxes, etc.) in real world situations, and it's an important skill to be able to think through things beyond the simplified approximations... Maybe even more important than the basic math. If you're going through all the trouble of writing a story problem and then turn around and end up abstracting things to an unrealistic degree anyway, then what was the point in the first place?
posted by Zalzidrax at 12:44 PM on May 15, 2010


The last question twoleftfeet asked is about 46.7 days if I've done the math correctly; lilypads are round, not hexagonal, so there would have to be overlap for them cover the entire lake.

Seriously?

Guys, think about this.

It doubles every day. It is half full. That is all the information you need to know to answer the question.
posted by empath at 12:53 PM on May 15, 2010 [1 favorite]


In a math class, yes. But far from all the information you would need to address an invasive species problem in a real pond. I think it's bad to be trying to teach mathematical literacy but at the same time teaching people that the correct answer is the one that requires them to use only a simple abstraction and stop thinking there, instead of trying to figure out how things will actually work.

For example, take this (trick) question:
A hunter spots ten ducks in a pond. He shoots one. How many ducks are left in the pond?

One dead one
posted by Zalzidrax at 1:37 PM on May 15, 2010


its a trick question about exponential growth, not a biology problem. If the answer isn't 1 day, then you're just pulling a number out of your ass.
posted by empath at 4:25 PM on May 15, 2010 [1 favorite]


You sure about that, empath?
posted by ODiV at 6:06 PM on May 15, 2010


oh, you know what, i misread the question as 'if it takes 48 days to cover half the lake, how long does it take to cover the rest of it'.... answer is 47.
posted by empath at 6:20 PM on May 15, 2010


*clamps hands over mouth but can't help the eyes glinting with glee*
posted by infini at 9:28 PM on May 15, 2010


Empath makes my point. I think making a mistake on these tests probably has more to do with not reading the question carefully than not understanding the math involved.
posted by chunking express at 7:01 AM on May 16, 2010


Or with understanding the rules of the lottery and interest. Also, if you're shopping at the speed of light, you just can't add the prices of the individual purchases together.
posted by Obscure Reference at 10:41 AM on May 16, 2010


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