On Sunday I will be talking about the paranormal at the Sunday Times Literary Festival in Oxford. If you are in the area, please come and say hello. OK, here is the puzzle….
You are given three boxes of fruit. One contains just apples, one contains just oranges, and one contains a mixture of apples and oranges. One box is labelled ‘apples’, one is labelled ‘oranges’, and one is labelled ‘apples and oranges’. None of the boxes is labeled correctly. Can you label the boxes correctly if you are only allowed to take and look at just one piece of fruit from just one of the boxes?
As ever, please feel free to say if you think you have solved it and how long it took, but do NOT post your answer. Have a good weekend and I will post the solution on Monday.
Yes. Took me about 5 seconds to figure it out.
Made a little grid of possibilities. It spills out logically from there. About a minute & a half total, making sure to walk through each box.
That’s what I did. I like this puzzle; mostly because I could solve it without getting a headache.
Me too! Usually puzzles are confusing and so are the answers if you have to simplify the decimal point and make into an improper fraction divided by the percentage of the AH!
Yes, just a few seconds.
Yes, I know the answer about swapping the labels to correctly mark the boxes, it is quite straightforward. It is hard to discuss without revealing the solution, so I will come back this afternoon to see how the comment trail is going!
Stephen
Yes, pretty straightforward. Took me about 5 seconds.
Just put “FRUIT” on each box, and you’re done
(10 seconds)
lol. nice.
Yeah.
Quick exercise, took me less than a minute. There is a single strategy what box to choose. Looking at a random fruit in this box will reveal what the correct label of all three boxes needs to be.
Exactly the way I did it. Less than a minute.
Yes, few secs
Well about ten minutes…..knew I could get one label right off but stumped after that……then reread the question and then …aah…. yes hunt for pen and paper…couldn’t do it in my head…..had to draw pictures….hehe …..but yes I think no problem now….. I could pick my snack in full confidence……I could have an apple or an orange…… :}
My girlfriend & I are arguing over who worked it out first but it took a few minutes.
Pretty straightforward, as long as i can choose the box. Otherwise, it’s impossible to solve.
Pretty quick and I’m feeling a bit worse for a pint and a half last night.
about 3 minutes, this was pretty easy
What fun. About ten seconds to intuit the right answer, and half a minute to work through it in my head to be sure.
nice puzzle…. i had to write down all the possibilities before i saw the answer, then it’s not so difficult (2min)
Took me just a minute or so at midnight after a couple glasses of wine. The fact that “none of the boxes are labeled correctly” as the puzzle states was what helped me.
Yes, but it took me ten minutes. I understood it wrong haha
Took me a minute, but I think I got it.
Yes! And I’ve just done a 12 hour night shift
Yes I could do that, it took me a couple of minutes to work out that i could do it- but I haven’t had any caffine yet!!
Yes, a couple of seconds with the answer, but then a minute or so to really convince myself it was right and there wasn’t a catch.
Yay – I got it in about 2 minutes. My diet of mainly saturated fats must be really helping them synapses kick in. Sorted.
Knew answer within seconds, another two minutes to prove on paper.
I’m off now to have a banana for beakfast.
Um, yes, pretty simple really. About a minute just to think it through
None of the boxes *is* labelled correctly.
Tsk!
Sorry! Corrected!
As Merriam-Webster’s Dictionary of English Usage puts it in their entry on “none”: “A specter is haunting English usage — the specter of the singular “none”. No one knows who set abroad the notion that “none” could only be singular, but abroad it is.”
Reputable and careful writers of British and American English have down the ages used both singular and plural verbs with “none”. “None of us are perfect”, says the Reverend Dr. Chasuble in Oscar Wilde’s The Importance of Being Earnest.
About 5 mins, not firing on all cylinders today
Yup. Intuitiated the answer in a few secs; a few secs more to think it through.
I like these kinds of puzzles. Took me about 2 minutes I would say.
Yep – nice and quick.
1sec seriousely
3 sec
Oh, hurray! Finally one that I can do. Thanks Dr Richard. I really enjoyed that.
Hmm… made me hungry… but got it too.
You are given three boxes. One contains an apple crumble, one contains an orange soufflé, and one contains a steamed apple, orange and ginger suet pudding. :p
Yes, I can. Joining the mob, 10 or 20 seconds to identify the relevant information, the same to have the complete solution. Very nice puzzle, thanks for it.
Less than a minute. But I needed paper and pencil.
Yup… took me a minute or so… easier than it first appears!
Yes… Three minutes… But then, I am also slow and deliberate at Sudoku.
easy 5 sec
Just one question, can you choose the box that you want to look into?
Yes! i can! this was an easy one! Less than a minute Hoera to me!
I knew the answer instantly, but then again I’ve seen this question in different forms before many times
about a min
happy i’ve finally got one
Zero seconds ‘cos I know this one of old.
Got my answer in about 30 secs and then took another couple of mins to draw my little diagram to double check.
Easy!
HA! Easy!
I’d squash all the fruits in the box and then taste the juice…. apple and orange hmmmm
I looked at it twice, the first time didn’t make any effort, the second time I read the text it took me 3 minutes to think of the solution and 6 to worth it correctly… interesting
took me a few seconds.
It’s interesting that the riddle looks complicated in the beginning but becomes simple real quick
I knew this kind of puzzle but to solve it u have to use scalling machine. I am not sure about this want….
Sir , do you want to share with my puzzle as well like this one?
The strategy only took a few seconds, then maybe a minute or two to work it out in my head.
Unless observed all the boxes contain a cat that is both alive and dead, so they’re all labelled incorrectly. Right?
I think this is one of those puzzles where you can prove what the answer must be by contradiction, without necessarily being able to construct a strategy that works with the correct number of samples.
I already knew the answer (a colleague of mine used it as a regular interview question), and I can’t remember how hard I found it the first time. The hardest thing is paying attention closely – there’s a crucial sentence that’s very easy to overlook the first time you read the question, and without which it is impossible.
Half an hour!
yes. took me only 0.021 seconds, couning from the moment i started reading the title.
these puzzles are getting easyer every friday…
Ha! It took me -0.021 seconds!
5 seconds.
it was too easy..
just saw and figured out..
This took 10 seconds. Until I realised I was wrong. Then another few minutes figuring out why, and sketching a proof for my answer!
Yup. About a minute or so. Used a grid like most people here.
Yes, its possible.
2 mins to read
1 minute to solve.. It’s more of a literature quiz 
yup, took me three mins, but that was cos I had to try to get the bit of paper I was double checking the answer on out from under my cats bottom when she decided it was THE place to have a wee sit down and rest on……
At last one that I solved at once.
got it after reading these comments and re reading question about 4 minutes
Took me about a min.
Had to lay it out visually to make sure I had everything straight, then it’s quite easy. You just have to make sure you use the information in the question properly.
“You just have to make sure you use the information in the question properly.” LOL
Yeah, I suppose that’s always the case, isn’t it?
Knew the answer in a couple of seconds but took me a minute to prove it.
Spent ages trying to figure it out. Re read the question.
Forgot to assume none of the boxes are labelled correctly.
Now have the answer!
Have an answer… not sure if it’s the right one. Took about 30 seconds.
yay got it!took about 5-10mins,feelin good about myself now!
A few seconds — knowing that it’s a PUZZLE and observing symmetries…
It’s a pretty simple logic game. Nice question.
Well it takes me a few minutes and a coffee:) the key is to choose the incorrect label correctly… lol!!!
Ah yes, instantly
took me about 2 minutes to figure out. Great fun!
This was a very fun puzzle! It took about 3 minutes from start to finish. It helped me to make a table of possibilities and I used little toys as the visual models.
Got it in a minute, which, in fact, was used to prove my answer correct. Didn’t we have this puzzle not too long ago with black and white balls or cubes or something? I do, however, like this kind of puzzle so much better than weird square root symbols.
Didn’t take long – maybe ten seconds.
Took me about 30 seconds. Fairly straightforward, just had to work through it.
Took me about 5 minutes to solve it
Used pen & paper.
Got the idea right away, too lazy to draw out a truth grid but it’s pretty straightforward I think.
Except when I work it out, no matter which way I go, the AO box is always O. That can’t be right. There must be a flaw in my thinking.
Ah, revised my thinking, figured out the trick. So it took a few minutes after all
Took me zero seconds. Saw it in that spanish film Fermat’s Room. I think.
it took us about one min to figure out
Yes, took me a minute with a piece of paper. I work better if I can sketch out scenarios. Now I hope I’m faced with this highly unlikely situation so I can be the hero of the day.
Nice question. I think I’ll use it to interview candidates (I manage programmers).
A minute or two to solve.
Bear in mind that programmers use such puzzles to weed out undesirable interviewers.
What happens if I get a banana?
Lucibee…..you can make a nice fruit salad when you are done…..hehe… :}
Half a second.
It’s not bad, but i’m kinda savvy in these kinds of puzzles.
It’s the mathematical ones i have trouble with… :S
too easy!
Wow everyone, how hard is it to not say the answers?
I got the answer in 1/40th of a second and want to stress the point to pretend that I’m much sharper than you.
About 3 minutes. I spent most of that time figuring out the number of ways the boxes could be mislabeled.
Just a few seconds for this one
… I’m having a tough time with the levitating girl in the previous post, though …
I like these kind of puzzles a lot more than (dubious) matchstick manipulation.
This one’s reasonably easy, but quite satisfying. Took a couple of minutes of solid thinking, and then another couple drawing it out on paper just to confirm my initial logic.
[...] It's the Friday puzzle! « Richard Wiseman's Blog [...]
Easy but it made me think. I like how these puzzles help me look at things in more than just the obvious ways.
Pretty sure I actually got this one this week! Took me a few minutes.
Made a grid. Took about 3 minutes to figure it out.
2mins was all it took to figure out in the head…….
no writings required for this one
2-4 sec to solve. Thanks!
Two minutes… as a mental challenge.
I sped up the process by imagining that the oranges was Durians, the thought of the smell pushed me along.
A few seconds, the first time I saw this puzzle many years ago. Fortunately, there are only two derangements of three objects, so remarkably one bit of information can suffice.
I really like this puzzle, took about 2 minutes, had to draw it out.
Yay – could actually do this one. Do I get a cookie and a gold star?
About a minute to make sure my answer worked.
heard this one too many times; had the answer in mind before I could even finish reading the way you expressed it.
In seconds
Yay, got it.
Took me some time to realise the details, all in all about 5 minutes and a spreadsheet.
I dunno about everyone else but i liked this one because to start with ti fels liek you’re only given a very small amount of info to go on but it’s actually pretty staight forward.
I’m not usually good at puzzles, so was pleased with myself for figuring this one out in about 5 mins. Pencil and paper needed though…
Yup, got it in just a few seconds, verified it with some quick figures.
Facil! I have 2 eyes…better!
Had a hypothesis about getting one box, but needed to write out a diagram to confirm and figure out the other boxes. Total time about 1 minute. I think this problem might be useful for teaching introductory statistics students the concept of degrees of freedom. Anybody agree?
I looked at it last night, but didn’t think much about it. This evening I saw it again and the answer was obvious. Maybe my subsconcience figured it out.
Took me about two seconds to think of the solution, and maybe fifteen to check my answer. Even while having a headache.
Easy. Half a second.
Pretty simple when you read the question closely, and don’t think of it in terms of what they are, but what they’re labeled, and a key word in the question.
A couple of minutes
I think I get this one. Can has cookie?
too easy
I haven’t look at the answer yet, even though it’s been posted, because I wanted to try to figure it out on my own. When I first looked at this, I saw no possible way, and was totally convinced this was just one of those ones I cant get. But! When a commenter reiterated the question, I noticed a key piece of the puzzle that I had overlooked. And I think I totally have it. 3 minutes from read to solution.
Hurrah, got it straight away. I never do that usually.