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?

The only card needed to prove the theory is the E. Because like Q and U you cannot have Q without U but you can have U without Q. Therefore you need not flip over the 4 to prove this theory.

Posted by james on 2005-02-22 01:48:53