16.29 Cathode-ray tubes. An electronics company manufactures several types of cathode-ray tubes on a mass production basis. To monitor the process, 50 tubes of a certain type were randomly sampled from the production line and inspected each day over a 1-month period. The number of defectives found each day is provided in the accompanying table.
a. Construct a p-chart for the sample fraction of defective cathode-ray tubes.
b. Locate the center line on the p-chart.
c. Locate the upper and lower control limits on the p-chart.
d. Does the process appear to be in control? If not, modify the control limits for future data. e. Conduct a runs analysis to detect a trend in the production process.