Question

The diameter of steel rods manufactured on two different extrusion machines is being investigated. Two random samples of sizes ?1 = 15 and ?2 = 17 are selected, and the sample means and sample variances are ?̅1 = 8.73, ?2 = 0.35, ?̅ = 8.68, and ?2 = 0.40, respectively.

a.Write down null and alternative hypotheses to test if the machines produce rods with different mean diameters.

b.What is the type of statistical test that is appropriate? Explain.

c.Test the hypotheses at ? = 0.05, using the critical value approach. What is your decision on null hypothesis(?0)? Interpret the test results.

d.What is the ? ????? for the test? Test the hypotheses using the ? ?????. Do you get the same answer as part (c)?

e. Construct a 95% confidence interval for the mean difference of diameters. Test the hypotheses using the confidence interval approach. Do you get the same answer as in parts (c) and (d)?

Answer 1