Consider the gear impact strength data in Exercise 10-24. Is there sufficient evidence to conclude that the variance of impact strength is different for the two suppliers? Use α = 0.05.

Exercise 10-24

(a) Is there evidence to support the claim that supplier 2 provides gears with higher mean impact strength? Use α = 0.05, and assume that both populations are normally distributed but the variances are not equal. What is the P-value for this test?

(b) Do the data support the claim that the mean impact strength of gears from supplier 2 is at least 25 foot-pounds higher than that of supplier 1? Make the same assumptions as in part (a).

(c) Construct a confidence interval estimate for the difference in mean impact strength, and explain how this interval could be used to answer the question posed regarding supplier-to-supplier differences.