Descriptive Statistics and Control Limits

A new machine has just been installed to cut and rough-shape large slugs. The slugs are then transferred to a precision grinder. One of the critical measurements is the outside diameter. The quality control inspector randomly selected five slugs each hour, measured the outside diameter, and recorded the results. The measurements (in millimeters) for the period 8:00 a.m. to 10:30 a.m follow.
Outside Diameter (millimeters)

Time 1 2 3 4 5
8:00 87.1 87.3 87.9 87.0 87.0
8.:30 86.9 88.5 87.6 87.5 87.4
9:00 87.5 88.4 86.9 87.6 88.2
9:30 86.0 88.0 87.2 87.6 87.1
10:00 87.1 87.1 87.1 87.1 87.1
10:30 88.0 86.2 87.4 87.3 87.8

question a. determine the control limits for the meanand the range
question b. Plot the control limits for the mean outside diameter and the range. hide problem

Step by step method for calculation of descriptive statistics is discussed here.