These tests are interesting because it illustrates two separate points quite well. First, let's take the tests, then I'll draw the morals for you. I first encountered the scheme used here in Daniel Dennett's book "Darwin's Dangerous Idea" (which I highly recommend), and I present it almost unchanged:
You have a set of cards before you. Each card has a letter on one side, and a number on the other.
----- ----- ----- ----- | D | | F | | 3 | | 7 | ----- ----- ----- -----
Now, let's say there's a condition that you're asked to check for. The condition is, "If there's a D on one side of the card, then there's a 3 on the other side." Which of the above cards do you need to flip over to see if that condition is met? Take your time, reason it out.
I won't tell you the answer yet. For now, let's move on to the second test.