A firm produces metal wheels. The mean diameter of the wheels should be 4 inches. Because of chance variation and other factors, the diameters of the wheels vary. To test whether the population average is really 4 inches, the firm selects a random sample of 100 wheels, and finds that the sample mean diameter equals 3.97 inches, and the sample standard deviation equals .14 inch. a What should the firm's decision be if they use 5% significance level? b What should the firm's decision be if they use 1% significance level