The proportion of credit-card holders who pay their bill in full each month is 20%; the other 80% make only a partial or no payment.
(a) In a random sample of 17 customers, what is the probability that:
i. 4 customers pay their bill in full?
ii. More than 4 customers pay their bill in full?
(b) What is the expected number of customers who credit card bill in full?
(c) What is the standard deviation?