Question

Some customers of a retail chain have a store credit card that earns them bonus gifts when they make purchases at the chain.​ Currently, 22 customers are shopping in a store in this chain. Of​ these, half already have a store credit card. If employees offer store credit cards to 5 of​ these, what is the probability that all of those chosen already have a​ card?

​(b) A family of 5 is shopping in the store. Noting that Subscript n Baseline Upper C Subscript xnCx gives the number of ways of picking a subset of x items out of​ n, what is the probability that the 5 randomly selected shoppers are in this​ family?

(c) How many possible subsets of those already having a card might the employees​ select?

d) Combine your answers to​ (b) and​ (c) to find the probability that all 5 of those offered credit already have a card.

Answer 1