11.) In a recent month, 88% of automobile drivers filled their vehicles with regular gasoline, 2% purchased midgrade gas, and 10% bought premium gas. Of those who bought regular gas, 28% paid with a...

11.) In a recent month, 88% of automobile drivers filled their vehicles with regular gasoline,  2% purchased midgrade gas, and 10% bought premium gas. Of those who bought regular  gas, 28% paid with a credit card. Of customers who bought midgrade and premium gas,

34% and 42%, respectively, paid with a credit card. Suppose we select a customer at  random.

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

b.) Find the probability that the customer paid with a credit card.

c.) Given that the customer paid with a credit card, find the probability that she or he  bought premium gas.