To increase sales, a cell phone store began giving a free month of service on some cell plan purchases. Customers were unaware whether they would receive the free month until after purchase. The store manager claimed that one in eight customers received the free month. Nine customers each buy a cell phone plan. Let X = the number of customers that receive a free month of cell phone service.

Part A:Is X a binomial random variable? Explain.

Part B:What is the mean and standard deviation of X? Provide an interpretation for each value in context.

Part C:Three of the nine customers receive a free month of service. Is the store's claim accurate? Compute P(X 3) and use the result to justify your answer.