Question 5 17 Marks A bookstore records show that 20% of customers making a purchase use a credit card to make payment. Assume that customer arrivals occur randomly and independently of one another. This morning 40 customers purchased books from store (a) Find the probability that less than 8 customers used the credit card. (3 Marks) (b) Find the probability that at least 8 customers but not more than 10 used the credit card. (3 Marks) (c) Find the probability that at least 25% customers will use the credit card. (4 Marks) (d) Find the probability that no customer will use the credit card. (3 Marks) (e) Find the expected and standard deviation of the number of customers who use credit cards. (4 Marks)