Question: A survey is being planned to determine the average amount of time chief executive officers of big corporations play golf. A pilot study with a small sample size indicated the mean time per week is 11 hours, with a standard deviation of 1.25 hours. It is desired to estimate the mean playing time within one-quarter hour with a 98 percent degree of confidence.

a. How many chief executive officers should be contacted in the survey to estimate the average weekly playing time?

b. If the confidence level were decreased to 92%, what would be the minimum sample size?