Recently I finished reading The Math Gene, by Keith Devlin. Here's a logic puzzle from the book.
Enjoy.
Imagine I lay four cards on a table in front of you. I tell you each card has a number on one side and a letter on the other. On the uppermost faces of the cards you see the four symbols:
E K 4 7 I then tell you that the cards are printed according to the rule: If a card has a vowel on one side, it has an even number on the other side.
Your task: which cards do you have to turn over to be sure that all four cards satisfy this rule?
First one to post the correct answer gets a prize recognition.
4 comments:
All four cards.
I pick E.
Rule states number conditional to vowel.
No rules stated on:
condition of number for a consonant
condition of letter for odd number
condition of letter for even number
Must turn:
E - if no even number on reverse, in violation
7 - if vowel on reverse, in violation
(the K and 4 are irrelevant regarding the rule)
Grubby for the win!
The only way a card can be in violation is if it has a vowel on one side and an odd number on the other, so therefore you need to check only cards that show either a vowel or an odd number.
Post a Comment