A bag contains 8 white, 6 black and 4 red discs. They are selected at random and not replaced. What is the probability that there is at least one black disc in the first four discs drawn out of the bag?

Answer 1

prob that the first 4 drawn contain NO black
= (12/18)(11/17)(10/16)(9/15) = 11/68

so prob of at least 1 black
= 1 - 11/68
= 57/68