Bob, a manufacturing plant manager, is inspecting the diameters of ball bearings produced by a suspected malfunctioning unit. He randomly selects a sample of 12 ball bearings and measures the diameters, which are as follows (in millimeters):
Sample 1 152 141 148
Sample 2 150 146 156
Sample 3 155 149 153
Sample 4 156 147 151
a) Construct a Mean Chart. Assume sample sizes of 3. Include the UCL and LCL. Is the process in control?
b) Construct a Range Chart.Assume sample sizes of 3. Include the UCL and LCL. Is the process in control?