A Sample of 35 Different Payroll Departments Found That Employees $240.6$

Multiple Choice

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 $\mu$ worked by all employees who are paid through payroll departments.

A) $230.9 < \mu < 250.3$
B) $236.8 < \mu < 244.4$
C) $232.4 < \mu < 248.8$
D) $235.4 < \mu < 245.8$