In Article <2tfv1n$t8d at cville-srv.wam.umd.edu>, bcohen at wam.umd.edu (Brad
>>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
>For a solution using the resampling method, contact pcbruce at wam.umd.edu)
Here's an unsophisticated answer; is there anything wrong with it?
The odds should be 50:50, assuming that we are talking about the first trick
being completely played. All south knows is that she saw a red ace, and a
red ace has been played. Therefore the chances of east and west having the
ace of hearts should be equal.
Department of Zoology, University of Alberta
wgallin at gpu.srv.ualberta.ca