6. Consider the hypothesis-testing problem in part (b) of Example 8.2-1. Thus, the null hypothesis is H0 : 28, 000. Let X denote

6. Consider the hypothesis-testing problem in part

(b) of Example 8.2-1. Thus, the null hypothesis is H0 : μ ≤ 28, 000. Let X denote the average tread life span of a random sample of n tires.

(a) The rule for rejecting this null hypothesis should be of the form X ≥ C, for some constant C > 28,000. True or false?

(b) Use the rationale of Example 8.2-2 to find C when the level of significance is chosen as α = 0.05, assuming that the population variance σ2 is known.

(c) Express the RR in terms of the standardized X.