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HARVARD STUDENTS GET near-perfect SAT scores (US college admission tests). These are smart, smart kids. So they shouldn’t have trouble with a simple logic question, right?
Try the following puzzle:
A bat and ball cost $1.10.
The bat costs one dollar more than the ball.
How much does the ball cost?
Scroll down for the answer …
Behavioral economist Daniel Kahneman explains why most people get this wrong:
A number came to your mind. The number, of course, is 10: 10¢. The distinctive mark of this easy puzzle is that it evokes an answer that is intuitive, appealing, and wrong. Do the math, and you will see. If the ball costs 10 ¢, then the total cost will be $1.20 (10¢ for the ball and $1.10 for the bat), not $1.10. The correct answer is 5¢. It is safe to assume that the intuitive answer also came to the mind of those who ended up with the correct number—they somehow managed to resist the intuition.
Many thousands of university students have answered the bat-and-ball puzzle, and the results are shocking. More than half of Harvard, MIT, and Princeton gave the intuitive – incorrect – answer. At less selective universities, the rate of demonstrable failure to check was in excess of 80 per cent. The bat-and-ball problem is our first encounter with an observation that will be a recurrent theme of this book: many people are overconfident, prone to place too much faith in their intuitions. They apparently find cognitive effort at least mildly unpleasant and avoid it as much as possible.
This excerpt comes from Kahneman’s 2011 book, Thinking, Fast And Slow, which posits that we have an intuitive mental system and a logical mental system, and we often use the wrong one at the wrong time.
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Thanks for making me feel dumb.
Is it bad that I’m still confused???
Lorraine, these cows are small and those ones are far away.
Forget Harvard….. I’m going to Yale..!!
I wouldn’t get in to Yale.
That’s the crowd that make locks right?
I think I just brain my damaged.
I must be thick. Still doesn’t make sense to me. :O
Thank you!
Me either haha
It’s not that hard lads.
If I had 5 cent. And you had a quid more than me, you would have $1.05.
Add them together and you get $1.10.
Its not hard when ya know how :D it just means i’m as clever as all those students in harvard and princeton that got it wrong! Go me! :D
Thanks god you explained that I thought I was really stupid but get it now.
That’s mad Ted !!
Is the answer still the same in euros?
i got the 5c alrite but instant thought was 10c for a sec,
Straight away I said 10c until I worked it out
where would I pick up this bargin? assuming it can be got?
I got 3 fiddy
My 9 year old got it right!
you nearly caused divorce in our car journey from Dublin to Cork anyway as I after some thought get it but my boyfriend is still swearing blind that its 10c for the ball!haha ….just cause he did honours maths and I didn’t….haha
I think 12 pubs of christmas last nite have cause brain damage i’m still not getting it
IM bad at maths but this one was easy. Deduct the difference between prices (1$) and divide the rest into two.
Thumbs up. That’s exactly the easy and best way to work it out, Kaja.
“Deduct the difference between prices (1$) and divide the rest into two”
No, it’s not INTO two – it’s BY two, or IN two, to get the price of the cheapest.
Oh my sainted aunt!
No wonder a pint costs 4.95 ….
@Barry: It was a maths teaser, not a grammar question!
How many of us got it right because we were told it was a tricky question and we took time to think about it?
Me! Wouldn’t have got it right but for the headline making me think twice
sugar frig and flip, excuse my language. I got it wrong.
Twelvty!
@thejournal Is there any chance you could post another brainteaser ASAP so’s we all can try get our dignity back.
i got it wrong. think i might have to rethink the career in accountancy
Paddy, I’ll do my best – but I might be fairer next time and not put it up on a Sunday after so many people appeared to have been out on the razz ;)
x+(x+100)=110
I got it right because when your in the pub trade you need to know how to count.
Like If a pint costs €4.50 and the government put 10c on the duty, the pint now costs €4.70……
But you don’t need to know the difference between your and you’re.
@Paul Martin, You will go far with a brain like yours.
That still doesn’t explain why I can get a pint of Guinness cheaper in central London than I can in St. James’ Gate.
Jesus Richard we get your in the pub trade every bloody comment of yours mentions you have a pub
r u in the pub trade first we heard of it
Paul Martin that was a good one. Laughing away here at that.
Frigging brilliant Paul Martin Ha ha that’s comment of the week .. I swear I pissed myself laughing your a comic
but you don’t need to know the correct time to use “your” and “you’re”…. FAIL
very clever ! reminds me when I first heard the think of a number trick ! think of a number , double it , add 8 , divide your ans by 2 , take away the number you first thought of and your answer is 4 !
I can count to orange!
Got it, yipee, now to
annoy everyone tonight by asking them to solve it
Still can’t work it out… $1 for bat, 10c for ball… Ball is 10c so a dollar more than that is $1.10…. What the flip am I not getting here?
eh a dollar more than 10c is 1.10 but then add 10c and it’s 1.20 a dollar more than 5c is 1.05 + 5c for the ball = 1.10
If the bat is $1 and the ball is 10c, then the bat is 90c more than the ball, not $1.
Bat = $1.05 …. Ball = 5c. Then the difference is $1.
Emmet the bat is one dollar ball is 10 cents. That’s a ninety cent difference. Do you get it now.
So, Batman did it?
If you hadn’t posted this the day after most of the country was on a Christmas pub crawl or a Christmas party I think there would be more positive comments here! At least that’s the excuse I’m going with for getting it wrong…
I still think it is 10c – I like living in ignorance bliss
Bat $1 , ball 10c = 90c difference. Bat $1.05 , ball 5c = $1 difference. That’s a clever question and there are millions of similar ones designed to catch people out, just like a con job, fool people, magic even, or a solemn promise not to reduce Child Benefit to get voted into power without ever intending to honour it cause its what you do at elections, like the 3 card trick.
Take a €1 coin. It’s weight is 23.25g.
Fill 20 tonne trucks with €1 coins, each truck bearing 20 tonnes of coins.
How many 20 tonne trucks will be required to pay the bond holders 3.1 billion Euro in March 2013?
Not only stupid but impractical…..
Ah Jaysus. Steady on there will ya. Not every thread here has to be a political one.
6,666,666.66
Pen and paper job, old school algebra worked it out. Very pleased with myself
”x + y = 1.10”
given that: x +1 = y
then replaying y gives: x+x+1 = 1.10
thus 2x=0.10
x=.05 => ball is 5 cent
I had it, but now I’m confused again
Im off to buy me a 5c Baseball. Shop around, you cant beat those prices.
After taking about 5 minutes but I figured it out!! Harvard here I come.
That was simple
I have always TOTALLY sucked at maths but I got this right. Why? Because I didn’t see it as a maths question, I immediately saw it as logical question.
Lol. And because it tells you it’s a logical question. :)
Damm it…I got it wrong…my head is sore…..I’m off to my local to annoy the crap out of everyone with this one….and pay the princely sum of €4.30 a pint for the privilege.
Cheaper to discuss over a game of rounders. Apparently
Just fell out with partner because he was adamant that the ball should be 10c
I got it right because it was in a book I had as a young kid – with a bottle and a cork.
I got it wrong then!
Thought it was 10c but realised if it was that easy they wouldn’t be asking the question so thought about it a bit more and got the answer right. Wohoo, very pleased with myself !
If the Publicans charged the right price for drink all ye mugs would be paying 6 euro a pint ye mugs.
No, there would be no publicans
so what exactly is the price of a keg of Heineken Richard? considering that the publican will sell it for 413 euro at 4.70 a pint I’d like to know the mark up
never mind Richard I looked it up. Heineken is ?255 a keg so it works out at ?2.90 per pint. price at my local is ?4.70 so that’s ?1.80 per pint profit for the publican. please explain how ?6 is the “proper” price of a pint?
It’s no mystery why off licences are cleaning up and pubs are shutting down. Especially if smug know nothings are pulling the pints.
gamma, to be fair, you ignored overheads.
you’re right there Shanners but you’re looking at a 40% mark up. that’s almost twice the markup on an off licence. do some homework and look at the cash profit on spirits and minerals in pubs. they’re even higher. overheads are well covered.
People still pay it so you can’t blame the publicans either. Now i must get back to the maths.
If there is such huge profits in the trade then why are so many closing. Its a tough, tough industry to be in. Overheads are huge. Not only the cost but the range of different overheads is massive.
Its like this there will allways be customers in the pub and most are mugs.I don’t drink myself and I own 2 houses in Ireland plus a flat in Spain.My family are proud of me.
To be fair they probably started out with low expectations.
Way to draw the customers the Richard. That news will get them flooding in no doubt.
You are such a sad individual Richard.
What do the lads down the pub think about that?
and sure didn’t he get five As in the Junior Cert as well.
I don’t believe that. I am really bad at maths and I got that easy peasy in seconds. Seriously, if that’s causing you problems you should be ashamed of yourself.
I got it but almost fell for it at the start. Pen and paper works it out simple enough
OK ..here is one for you….A loaf and a half for £1:50 how many would I buy for £8:00 ??
8?
5
For the love of god, dont leave us hanging!!!
8.
1 loaf = £1
Top of the class..
8
None – shops in this country only accept Euro
I’d still buy 1. Sure the rest would only go stale.
7 With change back!
As an Irish Harvard student, I can tell you that most Harvard students will get this right. Interestingly, it was a question on a psych study I recently completed in one of our labs.
Harvard – the place of dreams :D
Ha I got it right quite simple really ..
My Daughter’s name is Deirdre Maher :) Just saying :)
i got it right
made my day
thanks to the much maligned Bráithre Cristaí.
Harvard – here i come.
i got 54 cent,it has to be,5 cent me bollox,
In your face Harvard!
If I earn 42k€ in a year and the the tax & health insurance people take half
Then the publican & the taxes take the other half of what I spend; how many pints can I buy myself within the year?
Ha! Got it right! That’s a real project matches q.
$1.05 is a dollar more than 5c…
i got it wrong. think it might be time to rething the career in accountacny
I would have said .10 cent but that was the obvious answer…so after a little thought I actually got it right :-)
Hurrah ….I managed to avoid the intuitive answer ! I suggest that all our TDs, bankers and financial experts be given this question ! Dare I suggest what % would get it wrong ?
The hotel room is $25 and three guys want to share. They each pay their share with a $10 bill. The manager, who couldn’t figure how to divide the $5 among the three, keeps two dollars of the change and gives each man $1. So each man paid $9. 9×3 is $27, plus the $2 the manager kept is $29. Where did the other dollar go?
Each man got a dollar BACK, and the manager got $2 dollars back. Therefore the end should read as “So each man paid $9. 9×3 = $27, MINUS the $2 the manager kept is $25
A father and his son are in a car crash.
The father is killed instantly but the son survives with serious injuries.
The ambulance rushes him to hospital and he is taken straight to the theatre.
The surgeon arrives but, realising who it is says ‘ I cannot operate on him, he is my son’.
How can this be?
Darren the surgeon is the CHILDS MOTHER
I still don’t get it. The bat and ball cost 1.10 in total. How the hell did it jump to 1.20? This is a conspiracy God damn it!!
That was easy, The bat is $1.05 and the ball is 5 cents , maybe I should go to Harvard.
thicko here got it right , lol
I got it right but would never consider myself very logically minded! Where do I send my Harvard application?!
For those of you that are unable to figure it out, here’s another perspective. The answer is in the wording of the question..”the bat cost’s $1.00 MORE than the ball.” Therefore, if the ball costs .5c + $1.00(more) = $1.05. But remember to add your .5c for the ball to $1.05 which = $1.10
2x + 1 = 1.10 came to mind automatically though Im not sure why but it gave me the right answer
I believe Joseph Gladwell’s “Blink” goes against the author’s claim.
that was very easy, its basic math, does Kahneman’s book include more of these?
Glad I thought 1.05…..
A nice follow up question (after they tell you the answer for the first one) would be:
A bat and ball cost $11.0
The bat costs one dollar more than the ball
How much does the ball cost?
Does the tree make a sound when it falls in the forest ? This is the same question. Put out a simple question. Then give the wrong answer. And then sit back and watch a lot of clever people make fools of themselves !
Way hey, Harvard here I come!
this is basic math, does Kahneman’s book has more of these?
have your say