In a customer service center the average handling time for resolving customer inquries is monitored to ensure efficiency and quality of service the management wants to assess the process capability of this call handling time to ensure that it meets the desired service level agreement lets consider the following data mean handling time (x~): 8 minutes standard deviation of handling time 1.8 minutes upper specification limit (USL) 8+4 minutes lower specification limit (LSL) 8-4 minutes now we can use the formula for process capability index CP