A manufacturing process in the region produces a part where one of its specifications is the contact gap. The mean gap of the parts from this process should be 0.2355 inch with a standard deviation of 0.0168 inch, because the firm knows that each part's gap should be at least 0.185 inch and at most 0.286 inch to satisfy its customer's needs.
 

1. Rather than check each part, the company routinely and randomly selects 5 parts
    and computes their mean gap. Based on this information, it can set up limits for the
    sample means that it would expect to observe 95% of the time when the process is
    working well (this is called "in control"). What would these limits be?

2. Use the information in the file Gap2 to check what percent of the samples suggest
    the process might be out of control?

3. Graph the pattern through time to see if there are any patterns for the means that
    suggest out of control.
 
 

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