Mr Short, his sister, his son and his daughter are fond of golf and often play together. The following statements are true of their foursome:
1) The best player's twin and the worst player are of the opposite sex.
2) The best player and the worst player are the same age.
Question: Which one of the foursome is the best player?

This exercise is in the 12th Edition of: Introduction To Logic, by: Irving M. Copi - Carl Cohen. I can't decipher the answer, can you? Mike

The only possibility is that his daughter is the best player, assuming that his daughter and his sister are the same age (which could be possible). Putting any other player as the best player leads to contradictions.

The only possibility is that his daughter is the best player, assuming that his daughter and his sister are the same age (which could be possible). Putting any other player as the best player leads to contradictions.

It's also possible that his sister is the best player, which makes the daughter the worst player, and both sister and daughter the same age.