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Post by adpz on Apr 29, 2015 15:01:19 GMT -5
For anyone who cares, August 17th is not the correct answer. This is a tricky one, but making a box-chart of known/unknown states helps organize what is going on and get you to the answer. I'll play: a: There are two unique days 18 & 19. Since Albert says that he KNOWS Bernard does NOT know, then the months containing the 18th and 19th are OUT. This leaves us with only July and August as possible months. b: After the months are limited to July/August, Bernard says "now I know!" This means that the day only appears once in the set from July and August. 14 is repeated so we must conclude that the true answer is one of 15,16,17. c: Having seen that the true date is 15,16,17, Albert says "now I know too". This means that the correct month should only have one possibility from 15,16,17. That eliminates August (has 15,17) leaving only one possibility: Happy Birthday July 16 ! A+ ) It's a clever puzzle - when a friend originally sent it to me he said it was from a grade-school test (!) - but it came out a few days later that it was part of high school math Olympiad training in Singapore. Good job!!
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Post by greengeek on Apr 29, 2015 19:47:37 GMT -5
I'll play: a: There are two unique days 18 & 19. Since Albert says that he KNOWS Bernard does NOT know, then the months containing the 18th and 19th are OUT. This leaves us with only July and August as possible months. b: After the months are limited to July/August, Bernard says "now I know!" This means that the day only appears once in the set from July and August. 14 is repeated so we must conclude that the true answer is one of 15,16,17. c: Having seen that the true date is 15,16,17, Albert says "now I know too". This means that the correct month should only have one possibility from 15,16,17. That eliminates August (has 15,17) leaving only one possibility: Happy Birthday July 16 ! A+ ) It's a clever puzzle - when a friend originally sent it to me he said it was from a grade-school test (!) - but it came out a few days later that it was part of high school math Olympiad training in Singapore. Good job!! Its a good one...takes a moment's thought...
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