Some customers of a retail chain have a store credit card that earns them bonus gifts when they make purchases at the chain. Currently, 26 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 7 of these, what is the probability that all of those chosen already have a card?

A family of 7 is shopping in the store. Noting that nCx gives the number of ways of picking a subset of x items out of n, what is the probability that the 7 randomly selected shoppers are in this family?

The probability that the 7 randomly selected shoppers are in this family is