According to a May 2009 Harris Poll, 72% of those who drive and own cell phones say they use them to talk while they are driving. You wish to conduct a survey in your city to determine what percent of the drivers with cell phones use them to talk while driving. Use the national figure of 72% for your initial estimate of p.
a. Find the sample size if you want your estimate to be within 0.02 with 90% confidence.
b. Find the sample size if you want your estimate to be within 0.04 with 90% confidence.
c. Find the sample size if you want your estimate to be within 0.02 with 98% confidence.
d. What effect does changing the maximum error have on the sample size? Explain.
e. What effect does changing the level of confidence have on the sample size? Explain.