Question: A health club manager claims that members lose an average of 15 pounds during the first six months of membership. A sample of fifteen members of the club showed they lost an average of 11.5 pounds during the first six months of membership with a standard deviation of 2.2 pounds. Test at the 5% significance level if the mean weight loss during the first six months of their membership by all members of this health club is less than 15 pounds.