10. Costco Customer Satisfaction. Consumer Reports uses a 100-point customer satisfaction score to rate the nation's major chain stores. Assume that from past experience with the satisfaction rating score, a population standard deviation of o = 12 is expected. In one Consumer Reports survey, Costco, with its 432 warehouses ontent in 40 states, was the only chain store to earn an outstanding rating for overall quality. A sample of 15 Costco customer satisfaction scores follows. LO 3 95 90 83 75 95 98 80 83 82 93 86 80 94 64 62 Loy . == DATAfile Costco a. What is the sample mean customer satisfaction score for Costco? b. What is the sample variance? . What is the sample standard deviation? d. Construct a hypothesis test to determine whether the population standard deviation of = 12 should be rejected for Costco. With a 0.05 level of significance, what is your conclusion