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# What is a control chart?

1. What is a control chart? What are the grand mean, the UCL and the LCL of a control chart for the mean? Why do you suppose -3/+3 standard errors are used in control charts and not two standard errors or even one standard error? Explain.

2. A significance test is used to prevent a machine from underfilling or overfilling quart bottles. On the basis of a sample, the null hypothesis is rejected and the machine is shut down for inspection. A thorough examination reveals there is nothing wrong with the filling machine. From a statistical standpoint, was there a "type" error made? If yes, which type? Explain.

#### Solution Preview

1. A control chart is a visual representation of a process with the number of parts being produced plotted according to a parameter. The parameter can be a dimension of the part, number of defective parts produced, proportion of defective parts, or the like. The Grand mean ...

#### Solution Summary

This solution discusses control charts and significance test.

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