Chapter 8, Problem 45PS

What advertising medium is most influential in making a purchase decision? According to a TVB survey. $37.2\%$ of American adults point to TV. (Data extracted from “TV Seen Most Influential Ad Medium for Purchase Decisions." MC Marketing Charts, June 18, 2012.)

a. To conduct a follow-up study that would provide $95\%$ con�dence that the point estimate is correct to within $\pm 0.04$ of the population proportion. how large a sample size is required?

b. To conduct a follow-up study that would provide $99\%$ con�dence that the point estimate is correct to within $\pm 0.04$ of the population proportion. how many people need to be sampled?

c. To conduct a follow-up study that would provide 95% confidence that the point estimate is correct to within $\pm 0.02$ of the population proportion, how large a sample size is required?

d. To conduct a follow-up study that would provide $99\%$ con�dence that the point estimate is correct to within $\pm 0.02$ of the population proportion. how many people need to be sampled?

e. Discuss the effects on sample size requirements of changing the desired con�dence level-and the acceptable sampling error.