[chaosuk]

Now no one-up-man-ship here guys, don't spoil it for other folk if you simply know the answer. Good luck.

Every year, after the Christmas social at the Woodenhead Bridge Club, a party game is played. Four playing cards are randomly selected from a big box of used cards and stuck on the forehead of each of the four players sitting round a bridge table. Each person can only see the cards on the foreheads of the other three players. They each then attempt to guess correctly the colour, red or black, of their own cards. They do this by writing down their guesses on a piece of paper, so the others can't see what they've written. Up to three of them may also elect to write 'pass'. If, when the papers are revealed, one or more players have guessed the colour of their cards correctly the table gets a bottle of champagne. Any wrong guess, however, means they lose the prize. They may agree a strategy in advance but they mustn't speak or signal after the cards have been placed. They have a 50% chance of winning when one of the players guesses at random and the other three pass. How can they improve this to 75%?