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?
Turn over the E if it's not a 4 then the hypothesis is disproved.
If it is a 4, turn over the 7, if it's an E then the hypothesis is disproved. Otherwise the hypothesis is verified.
It doesn't matter whats on the other side of the 4, it may or may not be an E. Similarly the B could have a 4 on the other side.
Turn the E and 7
