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?

This problem is rather straightforward and simple.

When considering if-then statements, you need to know that the contrapositive is also true. In other words, we need to check "If A, then B" as well as "If not B, then not A."

"If A, then B." - Turn over the E to ensure a 4 is on the other side.

"If not B, then not A." - Turn over the 7 to ensure an E is NOT on the other side.

Posted by Eric on 2004-12-15 17:23:06