Historically,the Average Time to Service a Customer Complaint Has Been $\bar { X }$

Multiple Choice

Historically,the average time to service a customer complaint has been 3 days and the standard deviation has been 0.50 day.Management would like to specify the control limits for an $\bar { X }$ -chart with a sample size of 10 and 3 sigma limits.The UCL for the chart would be

A) less than or equal to 3.30.
B) greater than 3.30 but less than or equal to 3.40.
C) greater than 3.40 but less than or equal to 3.50.
D) greater than 3.50.