This week, The New York Times cited a puzzle that it claims is a chestnut, although I don’t recall seeing it before. You are presented with four cards, each of which contains a letter on one side and a number on the other. You are told that if a card has the letter “E,” then its reverse will be the number “5.” However, that statement might be false. Your four cards read E, 2, 5, and F. Which cards could help you determine the statement’s accuracy, and which would be unhelpful?
The answer is below. (Pause here if you wish to try the problem on your own.)
John Rekenthaler does not own shares in any of the securities mentioned above. Find out about Morningstar's editorial policies.