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 =12 is expected. In 2012, Costco with its 432 warehouses 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. 959083759598808382938680946462 b. What is the sample variance?