This exercise has been created as an aid to understanding the concept of a confidence interval. The worksheet Strength.MTW contains data for the tensile strengths (N/mm2) of a sample of 16 components. Assume that the production process for the components is known to operate with a standard deviation of 1.9 N/mm 2 . Verify, using Minitab, that in a z-test of H0:, = 50.0 versus H1 : 50.0 the decision would be to accept H0. Repeat the test for all the other null hypotheses listed in Table 7.21 and record your decisions. Note the range of values for the population mean, that would be accepted. By further changing of the mean value specified in the null hypothesis, determine, to 2 decimal places, the range of mean values that would be accepted. Check that the formula x l.96/ gives the same results apart form a small rounding error. The range of mean values that would be accepted is a 95% confidence interval for the mean tensile strength. Check that the 95% confidence interval provided by Minitab confirms your calculations. Obtain a 99% confidence interval for the mean tensile strength. Note that with greater confidence we now have