Tablet hardness. A pharmaceutical manufacturer forms tablets by compressinga granular

Chapter 0, Problem 11.15

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Tablet hardness. A pharmaceutical manufacturer forms tablets by compressinga granular material that contains the active ingredient and various fillers. Thehardness of a sample from each lot of tablets is measured in order to control thecompression process. The process has been operating in control with mean at thetarget value = 11.5 and estimated standard deviation = 0.2. Table 11.2gives three sets of data, each representing x for 20 successive samples of n = 4tablets. One set remains in control at the target value. In a second set, the processmean shifts suddenly to a new value. In a third, the process mean driftsgradually.(a) What are the center line and control limits for an x chart for this process?(b) Draw a separate x chart for each of the three data sets. Mark any points thatare beyond the control limits.