Test the validity of the equal-variance assumption for the data presented in problem 8–26.

In problem An article reports the results of an analysis of stock market returns before and after antitrust trials that resulted in the breakup of AT&T. The study concentrated on two periods: the pre-antitrust period of 1966 to 1973, denoted period 1, and the antitrust trial period of 1974 to 1981, called period 2. An equation similar to equation 8-7 was used to test for the existence of a difference in mean stock return during the two periods. Conduct a two-tailed test of equality of mean stock return in the population of all stocks before and during the antitrust trials using the following data: n1 = 21, x-bar1 = 0.105, s1 = 0.09; n2 = 28, x-bar1 = 0.1331, s2 = 0.122. Use α = 0.05.