Probability and statistics

Question

Prithi has two boxes. Box one contains three red, two silver, four gold, and two blue combs. She also has a second box containing one black and one clear brush. What is the probability that Prithi selects a red comb from box one and a black brush from box two?

 

Answer 1

Box 1 contains a total of 11 combs, of which 3 are red.  So the probability of choosing a red comb from that box is 3/11.

 

Box 2 contains 2 brushes, of which 1 is black.  So the probability of choosing the black brush is 1/2.

 

Since the two events are independent, the probability of BOTH of them happening is the product of the individual probabilities:  3/11 * 1/2 = 3/22