Smith Travel Research provides information on the one-night cost of hotel rooms throughout the United States (USA Today, July 8, 2002). Use $2 as the desired margin of error and $22.50 as the planning value for the population standard deviation to find the sample size recommended in (a), (b), and (c).
a. A 90% confidence interval estimate of the population mean cost of hotel rooms.
b. A 95% confidence interval estimate of the population mean cost of hotel rooms
c. A 99% confidence interval estimate of the population mean cost of hotel rooms.