Defective fuses. 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.