The personnel manager of a large corporation wishes to study absenteeism among clerical workers at the corporation's central office during the year. A random sample of 25 clerical workers indicated a mean of 9.7 days and a standard deviation of 4.0 days. We are interested in a 99% confidence interval estimate of the population mean number of absences for clerical workers.Which of the following is the correct 99% confidence interval:

Select one:

a. (5.7,13.7)b. (7.46,11.94)c. (8.05,11.35)d. (8.33,11.07)