Martin Gardner says that new mathematical puzzles are very
difficult to devise. What do you think of this one?
A slightly less-than-honest bridge player (south) caught a
glimpse of a card dealt to her opponent on the left (west) - it
was a red ace (she could not tell which suit). This opponent --
west -- opens the game by playing the ace of diamonds. South
sees that neither she nor the revealed cards of north have the
ace of hearts, which must be in either east's hand or west's
hand. What is the probability now that west has the ace of
Note: In bridge, four players are each dealt 13 cards from a
regular deck of cards. The one who initiates play is designated
west, the others east, north and south. North's hand is revealed
to all and the cards laid on the table.
For a solution using the resampling method, contact pcbruce at wam.umd.edu)