TV Ratings The CBS television show 60 Minutes has been successful for many years. That show recently had a share of 20, meaning that among the TV sets in use, 20% were tuned to 60 Minutes (based on data from Nielsen Media Research). Assume that this is based on a sample size of 4000 (typical for Nielsen surveys).

a. Construct a 97% confidence interval estimate of the proportion of all sets in use that were tuned to 60 Minutes at the time of the broadcast.

b. What sample size would be required to estimate the percentage of sets tuned to 60 Minutes if we wanted 99% confidence that the sample percentage is in error by no more than one-half of one percentage point? (Assume that we have no estimate of the proportion.)

c. At the time of this particular 60 Minutes broadcast, ABC ran “Exposed: Pro Wrestling,” and that show received a share of 11.

Based on the result from part (a), can we conclude that 60 Minutes had a greater proportion of viewers? Did professional wrestling really need to be exposed?

d. How is the confidence interval in part

(a) affected if, instead of randomly selected subjects, the survey data are based on 4000 television viewers volunteering to call an “800” number to register their responses?