10.21 How do ratings of TV and phone services compare? FileTelecom contains a rating of 13 different providers. a. At the 0.05level of significance, is there evidence of a difference in themean service rating between TV and phone services?
b. What assumption is necessary about the populationdistribution in order to perform this test?
c. Use a graphical method (show distribution, rejection andacceptance regions) to evaluate the validity of the assumption in(a).
d. Construct and interpret a 95% confidence interval estimate ofthe difference in the mean service rating between TV and phoneservices.
| Provider | TV | Internet | |
| Verizon FIOS | 71 | 71 | |
| AT&T U-verse | 70 | 69 | |
| Cox Communicaitons | 61 | 62 | |
| SuddenLink | 63 | 66 | |
| Optimum | 66 | 68 | |
| Comcast Xfinity | 58 | 60 | |
| TimeWarner | 60 | 62 | |
| Mediacom | 56 | 58 | |
| Spectrum | 63 | 65 | |
| Frontier Communications | 60 | 56 | |
