Suppose that 15% of the engines manufactured on a certain assembly line are defective, and engines are randomly selected one at a time and tested.
(a) Find the probability that exactly two defective engines will be tested before a good engine is found.
(b) Find the mean and variance of the number of defectives tested before the first good engine is found.
(c) Find the mean and variance of the number of defectives tested before the third good engine is found.