Question

The diameter of steel rods manufactured on two different extrusion machines is being investigated. Two random samples of sizes ?1 = 20 and ?2 = 24 are selected, and the sample means and sample variances are ?̅̅1̅ = 9.22, ?1 = 0.55, ?̅̅2̅ = 9.43, and ?2 = 0.62, respectively. Assume that ?1 2 = ?2 2 and that the data are drawn from a normal distribution. Is there evidence to support the claim that the two machines produce rods with different mean diameters? Use ? = 0.05.

a. Write the appropriate hypothesis.

b. Use P-value approach for hypothesis testing.

c. Use t-test for hypothesis testing.

d. Use confidence interval for hypothesis testing.

e. Clearly write your conclusion.

f. If the true mean difference is 0.4, find the type II error.

Answer 1