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pongo

Can you solve the maths question for Singapore schoolkids that went viral?

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Usually yes. These things usually turn into simultaneous equations...

 

...but not in the pub. :)

Edited by Albert Tatlock

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I challenge you to solve that using simultaneous equations. It's a logic question. :)

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if it was August, Albert could not initially know that Bernard did not know.

 

Edited - made silly error! Too.

Edited by pongo

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it's good isn't it ?

 

Am I right in thinking that a logic question like that cannot be expressed or solved using equations ?

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if it was August, Albert could not initially know that Bernard did not know.

Don't get you there - knowing it was August would allow him to say Bernard cannot know the answer - if he'd been told May June he could say "there is a chance Bernard knows", but with either August or July he can say "I know he doesn't know".

 

Edited - made silly error!

Edited by Chinahand

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it's good isn't it ?

 

Am I right in thinking that a logic question like that cannot be expressed or solved using equations ?

I've not studied formal logic, but there are very abreviated grammars which make it easier to follow the path through. Maybe not as clear as an equation, but still close.

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Now we're both wrong differently. Only if it were May or June could Bernard know.

  • Like 1

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Christ - Sorry Pongo, that is what I meant, but wrote it wrong - May or June would allow Albert to say Bernard may know! Edited it now to make it right!

Edited by Chinahand

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Even after reading the answer I don't get it!

 

"Albert: I don’t know when Cheryl’s birthday is, but I know that Bernard doesn’t know too." - fine that rules out May and June.

 

"Bernard: At first I don’t know when Cheryl’s birthday is, but now I know." this rules out 14.

 

Bernard has been told 15, 16, or 17. He can work out the answer.

 

Albert has been told July or August. So it can only be one of three: July 16, Aug 15 or Aug 17. I can't see how to get from there to the answer.

Edited by Mr. Sausages

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It's a mental tongue twister even when you can see how obvious it is.

 

It's a clever question.

 

ETA: that was reply to Chinahand not Mr Sausages

Edited by pongo

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Do you know this one:

 

Imagine a monastery in which ten of the monks may have a disease which causes them to have blue spots on their foreheads but has no other symptoms. All the monks have taken a vow of silence, they meet just once a day, and there are no mirrors in the monastery, so nobody knows whether he has a blue spot on his forehead or not.

If a monk discovers that he has a blue spot on his forehead, he will have to leave the monastery by the end of the day. All the monks are perfect logicians – that is, they can instantly infer all the logical consequences of any statement made to them – and they all know that all the other monks are perfect logicians.

One day, the Guru, who is known to be truthful, gathers all the monks together and announces “At least one monk in this monastery has a blue spot on his forehead.” Nothing happens for nine days, but on the tenth day, all the monks with blue spots leave.

How many monks left and why?

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Even after reading the answer I don't get it!

 

"Albert: I dont know when Cheryls birthday is, but I know that Bernard doesnt know too." - fine that rules out May and June.

 

"Bernard: At first I dont know when Cheryls birthday is, but now I know." this rules out 14.

 

Bernard has been told 15, 16, or 17. He can work out the answer.

 

Albert has been told July or August. So it can only be one of three: July 16, Aug 15 or Aug 17. I can't see how to get from there to the answer from there.

Bernard has been told a day. He's worked it out.

 

Albert has been told a month - because he knows the month, he now knows the exact birthday,

not a guess of two different days

. So what is the month he's been given?

Edited by Chinahand
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