Test the validity of the equal-variance assumption in problem 8-27.

In problem The cosmetics giant Avon Products recently hired a new advertising firm to promote its products. Suppose that following the airing of a random set of 8 commercials made by the new firm, company sales rose an average of 3% and the standard deviation was 2%. For a random set of 10 airings of commercials by the old advertising firm, average sales rise was 2.3% and the standard deviation was 2.1%. Is there evidence that the new advertising firm hired by Avon is more effective than the old one? Explain.