Chip Technologies manufactures personal computers for large chain electronic retail outlets. Each day several orders are selected at random and each computer carefully inspected against a check list. The total defects are recorded and plotted on a control chart. Since orders vary in size, the total number of computers inspected differs each day. The results for 20 days of inspection are shown in the table below.
a. Analyze this process using an appropriate control chart. What would be your recommendations to the plant manager?
b. A Six Sigma team was formed to investigate the defect problem. Some changes were implemented, aimed at stabilizing the process. After all workers had been thoroughly trained in the new procedures, data were collected for a 20-day period and are summarized in the table.

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Number of Number of Day Computers Number of Day Computers Number of Defects Defects Inspected 15 27 18 36 25 16 37 23 19 26 Inspected 18 16 32 16 17 37 19 37 32 36 35 27 70 69 78 21 12 13 14 15 16 17 98 31 15 147 32 106 34 101 71 65 19 20 82