Problem 8.45 In a comparison study of two independent normal populations the sample variances were s2 1 = 1.1 and s2 2 = 3.4, and the corresponding sample sizes were n1 = 6, n2 = 10. Is one justified in using the two sample t test? Justify your conclusions.

Problem 8.46

(a) Refer to the data set of Problem 1.7. Construct a Q–Q plot to assess, informally, the plausibility of the normality hypothesis. Comment on whether or not the points (zj , x(j)) appear to lie along a straight line.

(b) Test the data for normality by applying the Shapiro–Wilk test. State the alternatives, decision rule, and conclusion.