Each time that a shopper purchases a tube of toothpaste, he chooses either brand A or brand B. Suppose that the probability is 1/3 that he will choose the same brand chosen on his previous purchase, and the probability is 2/3 that he will switch brands.
(a) If his first purchase is brand A, what is the probability that his fifth purchase wil1 be brand B1 :+
(b) If his first purchase is brand B, what is the probability that his fifth purchase will be brand B?