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# Control Chart and Standard Deviations

Bill Kime's bowling ball factory makes bowling balls of adult size and weight only. The standard deviation in the weight of a bowling ball produced at the factory is known to be 0.12 pounds. Each day for 24 days, the average weight, in pounds, of nine of the bowling balls produced that day has been assessed as follows:

Day Average (lb) Day Average (lb)
1 16.3 13 16.3
2 15.9 14 15.9
3 15.8 15 16.3
4 15.5 16 16.2
5 16.3 17 16.1
6 16.2 18 15.9
7 16.0 19 16.2
8 16.1 20 15.9
9 15.9 21 15.9
10 16.2 22 16.0
11 15.9 23 15.5
12 15.9 24 15.8

A) Establish a control chart for monitoring the average weights of the bowling balls in which the upper and lower control limits are each two standard deviations from the mean. What are the values of the control limits?

B) If three standard deviations are used in the chart, how do these values change? Why?

#### Solution Preview

I completed the chart. I used the easier method of getting the upper and lower limits in each level of standard deviation. could not make the marks turn into lines and I am not sure why. However, you can see in the legend which is the noted data and points.

Click on any of the ...

#### Solution Summary

The solution assists with establishing a control chart and discusses how value change based on the standard deviations.

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