A sample of 35 different payroll departments found that employees worked an average of 240.6 days a year. If the population standard deviation is 18....

A sample of 35 different payroll departments found that employees worked an average of 240.6 days a year. If the population standard deviation is 18.8 days, find the 90% confidence interval for the average number of days worked by all employees who are paid through payroll departments.