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 09.
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
re(2): Solution by Sean)
If you turned over the 7, there might be an E on the back. That would disprove the hypothesis.
And what they were saying before wasn't "If E, then 4, therefore: If 4, then E". Using your example about squares being quadrilaterals, but not all quadrilaterals being squares:
If a shape is a square, it is definitely a quadrilateral.
If a shape is not a quadrilateral, then it is definitely not a square
So, if you have a number that isn't a 4, an E cannot be on the back, and you must look under the 7 to make sure.
Edited on March 6, 2005, 11:20 pm

Posted by Dustin
on 20050306 23:14:23 