I present to you a deck of 4 cards. Each card has on one side a letter of the alphabet, and on the other side a single digit from 0-9.

I propose a hypothesis that may apply to this deck:
If the letter is 'E', then the number on the other side is '4'.

I then drop the 4 cards on the table, and you see: 'B', '7', 'E', '4' (on the respective cards).

Which of the 4 cards must you turn over to verify or disprove my hypothesis?

(In reply to re: Solution by artemis)

I know that the problem doesn't say that E is 4. I'm saying that you have to imagine that it is, to understand it more clearly. The proposition that the problem poses is that when there is an E, there is a 4 (so, in a sense, E is 4). So, to test that argument, you have to see whether or not there will be a 4 when there is an E. It can't be any other way. Turning over any other card would be irrelevant to proving or disproving the hypothesis. If you turned over 4 and saw an A, that doesn't prove or disprove anything, since the problem didn't say that when there is 4, there is whatever. And, for this same reason, turning over B or 7 doesn't do anything, either.

I hope you understand me better, now. Sorry if I wasn't exactly clear before.

Posted by Sean on 2005-03-06 23:08:48