A manufacturer of computer terminal fuses wants to establish a control chart to monitor the production process. Each hour, for a period of 25 hours, during a time when the process is known to be in control, a quality control engineer randomly selected and tested 100 fuses from the production line. The number of defective fuses found each hour is recorded in the table.

a. Construct a p-chart for the sample percentage of defective terminal fuses.

b. Locate the center line on the p-chart.

c. Locate upper and lower control limits on the p-chart. Does the process appear to be in control?

d. Conduct a runs analysis on the points on the p-chart. What does this imply?

e. Suppose the next sample of 100 terminal fuses selected from the production line contains 11 defectives. Is the process now out of control? Explain.

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CTFUSE Нour 1 2 3 4 5 6 7 8 9 10 Number Defective 6 4 9 3 0 6 4 2 1 2 Hour 11 12 13 14 15 16 17 18 19 20 Number Defective 1 3 4 5 5 2 1 1 1 0 Hour 21 22 23 24 25 Number Defective 7 9 2 10 3