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 Is there a catch ? by Syzygy)

The catch is that even if the "E" card has a "4" on its back, the "7" card could have an "E" on its back, and you wouldn't realize it.

Posted by Federico Kereki on 2004-12-15 15:23:50