Purchases made at a store have a 80% chance of being paid using credit card. Using this fact, determine the answer to the following questions:

a. What are the chances the purchase is NOT paid with credit card?

Suppose we look at 15 randomly selected shoppers

b. What is the probability that at least 10 of them pay with credit card?

c. What is the probability that exactly 12 of them pay with credit card?

d. What is the probability that less than half of them pay with credit card?