To improve service quality, the owner of a dry-cleaning business has the business objective of reducing the number of dry-cleaned items that are returned for rework per day. Records were kept for a four-week period (the store is open Monday through Saturday), with the results given in the following table and in the file Dryclean.

a. Construct a chart for the number of items per day that are returned for rework. Do you think the process is in a state of statistical control?
b. Should the owner of the dry-cleaning store take action to investigate why 12 items were returned for rework on Day 12? Explain. Would your answer change if 20 items were returned for rework on Day 12?
c. On the basis of the results in (a), what should the owner of the dry-cleaning store do to reduce the number of items per day that are returned for rework?

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Items Returned Items Returned Dayfor Rework Da for Rework 16 10 18 19 21 10 12 12