A record store owner assesses customers entering the store as high school age, college age, or older, and finds that among all customers 30%, 50%, and 20% respectively, fall into these

categories. The owner also found that purchases were made by 20% of high school age

customers, by 60% of college age customers, and by 80% of older customers.

(a) Find the probability that a randomly chosen customer will make a purchase?

(b) If a customer makes a purchase, what is the probability that this customer is of college

age?