Hi Martin

I assume that there are 4 cards on the board, and you do not have a club. There are 46 unseen cards, and 9 clubs left. You now have to calculate the probability that he does NOT have a club. Of 46 cards 37 are not clubs.
(37/46)*(36/45) = 64%. So in 36% of they time he will have one or more clubs.

Jesper Jørgensen, Denmark