An extrusion die is used to produce aluminum rods The diamet

An extrusion die is used to produce aluminum rods. The diameter of the rods is a critical quality characteristic. The following table shows values for 20 samples of three rods each. Specifications on the rods are 0.4030 plusminus 0.0010 inch. The values given are the last three digits of the measurement; that is, 36 is read as 0.4036. Using all the data, find trial control limits for X and R charts, construct the chart, and plot the data. Use the trial control limits from part (a) to identity out-of-control points. If necessary, revise your control limits, assuming that any samples that plot outside the control limits can be eliminated. Twenty samples of size 4 are drawn from a process at 1-hour intervals, and the following data are obtained: Find trial control limits for X and R charts. Assuming that the process is in control, estimate the process mean and standard deviation. The overall length of a skew used in a knee replacement device is monitored using X and R charts. The following table gives the length for 20 samples of size 4. (Measurements are coded from 2.00 mm; that is, 15 is 2.15 mm.)

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