Academic

More Gladwell Brainteasers

By Jacqueline Lipton

So I've just finished reading "The Tipping Point" by Malcolm Gladwell.  Here's a puzzle from page 159 for readers' amusement...

"Suppose I give you four cards labeled with the letters A and D and with the numerals 3 and 6.  The rule of the game is that a card with a vowel on it always has an even number on the other side.  Which of the cards would you have to turn over to prove this rule to be true?"

Answer below the fold...

"The answer is two:  the A card and the three card."

You don't have to turn over the 6 card because it doesn't matter whether that card has a vowel or a consonant on the other side.  The rule of the game is only that a card with a vowel on it always has an even number on the other side, not vice versa. 

You don't have to turn over the D card because the game has no rule about what is on the other side of a card with a consonant on the front.

Full post as published by The Faculty Lounge on June 25, 2009 (boomark / email).