Control Charts: An engineer for Jordan Valley Tool Company specified that the diameter of a particular part should have tolerance limits of .352 and .356. An assistant to the controller asked production personnel to sample these parts. A random sample of 20 parts had the following diameters:

The mean and standard deviation of the diameter for this type of part has been established as .354 and .003. respectively. Jordan Valley Tool management established a policy that variances outside of the two-sigma limit should be investigated. By contrast, engineering and production personnel believe a process is in control as long as variances are within three standard deviations from the mean.

Required:

a. Construct a control chart and plot the sample on it.

b. Are the engineer's tolerance limits currently attainable? If not, what alternatives are open to the company?

Transcribed Image Text:

Exhibit A (25-32) Number Diameter .351 123456969 .350 .353 .352 .359 .360 7 .362 8 .351 .353 10 .358 11 .355 12 13 14 15 16 17 18 2345678 .350 .353 .354 353 354 .355 .355 19 .356 20 .354