A cage contains 5 black and 4 white mice that are available for a biology experiment.

Question

Three mice are selected at random. What is the probability that at least one is black and at least one is white?

Answer 1

If there are 9 mice in total and 3 are chosen at random, then there is a 1/3 chance that ANY mouse will be chosen regardless of color. However, the odds that they are going to be Black is 1/3 * 5/9 = 5/27 and the probability that the mouse will be White is 1/3 * 4/9.