5. Sales: Paint A chain of hardware stores is trying to sell more paint by mailing pamphlets describing the paint. In 15 communities containing one of these hardware stores, the paint sales (in dollars) were recorded for the months before and after the ads were sent out. The paired results for each store follow.

Sales after 610 150 790 288 715 465 280 640 500 118 265 365 93 217 280 Sales before 460 216 640 250 685 430 220 470 370 118 117 360 93 291 430 Use a 0.01 level of significance to test the null hypothesis that the advertising had no effect on sales against the alternate hypothesis that it improved sales.