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. 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 is contained in the Excel screenshot below. I need help with questions a$.$ b$.$ c$.$and d$.$