The Kaiser Family Foundation released a study about the influence of media in the lives of young people aged 8−18. In the study, 17% of the youth were classified as light media users, 62% were classified as moderate media users, and 21% were classified as heavy media users. Of the light users who responded, 74% described their grades as good (A’s and B’s), while only 68% of the moderate users and 52% of the heavy users described their grades as good. Suppose that we select one young person from the study at random.

a. Draw a tree diagram to model this chance process.

b. Find the probability that this person describes his or her grades as good.

c. Suppose the chosen person describes his or her grades as good. What’s the probability that he or she is a heavy user of media?