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Developing Mean and Range Chart

Twelve sample, each containing five parts, were taken from a process that produces steel rods. The length of each rod in the samples was determined. The results were tabulated and sample means and ranges were computed. The results were:

SAMPLE SAMPLE MEAN (in) RANGE (in)
1 10.002 0.011
2 10.002 0.014
3 9.991 0.007
4 10.006 0.022
5 9.997 0.013
6 9.999 0.012
7 10.001 0.008
8 10.005 0.013
9 9.995 0.004
10 10.001 0.011
11 10.001 0.014
12 10.006 0.009

a) Determine the upper and lower control limits and the overall means for x-charts and R-charts.
b) Draw the charts and plot the values of the sample means and ranges.
c) Do the data indicate a process that is in control?
d) Why or why not?

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Solution Summary

This solution develops and analyzes the mean and range charts for the given process in an Excel file. It determines the grand mean, average of sample ranges, central line, upper control limit, lower control limit and graphs the relationship.

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