The management of a franchised restaurant chain is in the process of establishing quality control charts for the time that its service people give to each customer. Management thinks the length of time that each customer is given should remain within certain limits to enhance service quality. Four employees were observed 6 times. The activities that the service people were performing were identiited, and the time to service one customer was recorded as noted below:
Mary Bill Sue Tom
observation 1 200 150 175 90
observation 2 120 85 105 75
observation 3 83 93 130 150
observation 4 68 450 145 175
observation 5 110 90 75 105
observation 6 115 65 115 125
A2 = 0.48 D3 = 0 D4 = 2.00 n = 6
Calculate the upper (UCL) and lower (LCL) control limits for an X chart n = 6
Calculate the upper (UCL) and Lower (LCL) control limits an R chart n = 6