A firm wishes to set up Mean and Range charts for lathes producing steel shafts of diameter 2 inches. Five samples are taken, each of size 4, and the diameters are measured. Sample Observation 1 2 3 4 1 1.96 2.01 2.04 1.97 2 2.05 2.02 1.93 1.99 3 1.98 1.95 2.02 2.05 4 2.03 1.98 1.97 2.00 5 1.9 2.01 1.97 2.04
a. Find the appropriate control limits.
b. After the control limits have been established, a sample of size 4 is taken and inspected. The diameters are as follows: 1.92, 1.97, 2.08, 1.95 inches. Does the process appear to be in control?
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