10.21 How do the ratings of TV and Internet services compare?The file Telecom contains the rating of 14 different providers.(Data extracted from "Ratings: TV, Phone, and Internet Services,"Consumer Reports, May

2014, pp. 28-29.) a. At the 0.05 level of significance, is there evidence of a difference in the mean service rating between TV and Internet services? b. What assumption is necessary about the population distribution in order to perform this test? c. Use a graphical method to evaluate the validity of the assumption in (a). d. Construct and interpret a 95% confidence interval estimate of the difference in the mean service rating between TV and Internet services.