pongo Posted April 13, 2015 Share Posted April 13, 2015 Can you solve the maths question for Singapore schoolkids that went viral? 2 Quote Link to comment Share on other sites More sharing options...
Albert Tatlock Posted April 13, 2015 Share Posted April 13, 2015 (edited) Usually yes. These things usually turn into simultaneous equations... ...but not in the pub. Edited April 13, 2015 by Albert Tatlock Quote Link to comment Share on other sites More sharing options...
pongo Posted April 13, 2015 Author Share Posted April 13, 2015 I challenge you to solve that using simultaneous equations. It's a logic question. Quote Link to comment Share on other sites More sharing options...
Chinahand Posted April 13, 2015 Share Posted April 13, 2015 17 August - I think! Quote Link to comment Share on other sites More sharing options...
pongo Posted April 13, 2015 Author Share Posted April 13, 2015 (edited) if it was August, Albert could not initially know that Bernard did not know. Edited - made silly error! Too. Edited April 13, 2015 by pongo Quote Link to comment Share on other sites More sharing options...
Chinahand Posted April 13, 2015 Share Posted April 13, 2015 Opps! Got it! 1 Quote Link to comment Share on other sites More sharing options...
pongo Posted April 13, 2015 Author Share Posted April 13, 2015 it's good isn't it ? Am I right in thinking that a logic question like that cannot be expressed or solved using equations ? Quote Link to comment Share on other sites More sharing options...
Chinahand Posted April 13, 2015 Share Posted April 13, 2015 (edited) 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 April 13, 2015 by Chinahand Quote Link to comment Share on other sites More sharing options...
Chinahand Posted April 13, 2015 Share Posted April 13, 2015 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. Quote Link to comment Share on other sites More sharing options...
pongo Posted April 13, 2015 Author Share Posted April 13, 2015 Now we're both wrong differently. Only if it were May or June could Bernard know. 1 Quote Link to comment Share on other sites More sharing options...
Chinahand Posted April 13, 2015 Share Posted April 13, 2015 (edited) 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 April 13, 2015 by Chinahand Quote Link to comment Share on other sites More sharing options...
Mr. Sausages Posted April 13, 2015 Share Posted April 13, 2015 (edited) 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 April 13, 2015 by Mr. Sausages Quote Link to comment Share on other sites More sharing options...
pongo Posted April 13, 2015 Author Share Posted April 13, 2015 (edited) 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 April 13, 2015 by pongo Quote Link to comment Share on other sites More sharing options...
Chinahand Posted April 13, 2015 Share Posted April 13, 2015 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? Quote Link to comment Share on other sites More sharing options...
Chinahand Posted April 13, 2015 Share Posted April 13, 2015 (edited) 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 April 14, 2015 by Chinahand 1 Quote Link to comment Share on other sites More sharing options...
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