Can you solve it ?

[MJMcCready]

(please keep the answer to yourself if so rather than posting it so that others can try)

11076261_1396681013982900_2028865334891680727_n.jpg

[MJMcCready]

Took me a while but I got there.

[Andy Stoker]

Got it quickly (<5 seconds) but only - I suspect - because I've seen something similar before .... as well as being a genius

[MartinCarpenter]

I find these things rather hard, because the real answer is always anything at all That's even if they have to be in a sequence produced by a formula.....

[David Gilbert]

I find these things rather hard, because the real answer is always anything at all That's even if they have to be in a sequence produced by a formula.....

It depends which way you look at it.

[Christopher Kreuzer]

About a minute before I twigged and solved it. But might have taken me longer if I had not spotted it.

[Ray Sayers]

Very funny. I guess children have less preconceptions than adults!

[David Robertson]

That was a whole lot easier than the damn Singapore test

[Kevin Thurlow]

"That was a whole lot easier than the damn Singapore test"

True - I sent the Singapore one to a couple of maths experts and they got it fairly quickly. I had to read the explanation a couple of times, before I understood it! It is possible that the Singaporeans practise such things of course, which makes it easier, but not easy.

Chess players should get the one at the top of the thread, as it requires thinking in a logical way.

[MartinCarpenter]

Very funny. I guess children have less preconceptions than adults!

Well, yes/no

If you look at the problem with no preconceptions at all then its a very silly question as the answer genuinely could be any number at all.

If you assume it somehow maps to the reality of a car park somewhere (why?) then I can see what people might think is the answer, but frankly I wouldn't be terribly confident of it in real life. Numbered car parks are rather rare and people do quite often do odd things when creating such things!

If you map it to the actual reality of a badly drawn picture on a computer screen then its even sillier because there isn't any 'under' for the hypothetical number to be in!

There's a 'socially' expected answer to these sorts of things of course but it doesn't bother me

That Singapore question looks really rather vaguely phrased to me, even with the clarification.....

[David Robertson]

That Singapore question looks really rather vaguely phrased to me, even with the clarification.....

No good blaming the examiner! Man up, and solve the wretched thing! It did my head in

[Carl Hibbard]

87 it's an optical one.

[MartinCarpenter]

Surely I'm allowed to pedant maths exams?

At a minimum you have to clarify the total absence of a priori knowledge - as posed the two people they might very plausibly know that some of the dates weren't possible options - and then disambiguate the nature/timing of the conversation between them.

There's even an entirely consistent explanation of the problem as set involving Bernard simply being told (or knowing) the day then him (in between two of those statements) telling Albert
(This would be rather non trivial to encode in formal logic mind you. Both time and belief about other entities knowledge involved....).

[MJMcCready]

That was a whole lot easier than the damn Singapore test

That is ridiculously hard, does anyone know the answer and why?

[Michael Farthing]

July 16

Bernard could only know the answer if it was on a day of the month that features only once: May 19 or June 18
Albert knows that Bernard does not know, so he must know that the month is neither May nor June
As soon as Bernard hears this he has the answer - which must be a date that only appears once in the months of July and August
The possibilities are July 16, August 15 and August 17 (excluding July 14 and August 14)
Albert now knows the answer, which must be July 16 as if the date was in August Albert still would be unable to choose between 15 and 17