A publisher is interested in the effects on sales of college texts of expensive three-color cover designs. The publisher is planning to bring out twenty texts in the business area and randomly chooses ten of them to have expensive cover designs. The remaining ten are produced with plain covers. For those with expensive cover designs, first-year sales aver- aged 9,254, and the sample standard deviation was 2,107. For the books with plain cover designs, average first-year sales were 8,167, and the sample standard deviation was 1,681. Assuming that the two population distributions are normal with the same variance, lest the null hypothesis that the population means are equal against the alternative that the true mean is higher for books with expensive cover designs.