Question

A box contains four balls One red ball, one blue ball, and two green balls. We repeatedly draw a random ball from the box with replacement until we have chosen at least oneball of each of three colors. Find E(Y), whereY is the number of draws.

Answer 1

1/32

Explanation:

First find the probability of picking red, blue and green balls respectively. The probability of picking any of the green balls are equivalent since only one ball of each colour should be picked. The detailed solution is found in the image attached. They are independent events so we multiply the probabilities.