Question: A company is interested in estimating the mean number of days sick leave taken by all its employees. The firm's statistician selects a random 65 personnel files and notes the number of sick days taken by each employee. The sample had a mean of 15.8 days with s = 10.7 days.

a) Estimate a 95% confidence interval for the mean. Interpret results.

b) State the margin of error and interpret its meaning in terms of problem.

c) How many personnel files would the statistician have to select in order to estimate the mean to within 1 day with 95% confidence?