Researchers are testing commercial air-filtering systems made by the Winston Industrial Supply Company and the Barrington Filter Company. Random samples are tested for each company, and the filtering efficiency is scored on Winston Barrington a standard scale, with the results shown in the margin. (Higher scores respond to better filtering.) At the 0.05 level of significance, test the claim that x = 85.7 x = 80.6 both systems have the same mean.