To construct a p-chart for a manufacturing process, 25 samples of size 200 were drawn from the process. The number of defectives in each sample is listed in time order in the table that follows.

a. Calculate the proportion defective in each sample.
b. Calculate and plot p and the upper and lower control limits for the p-chart.
c. Calculate and plot the A, B, and C zone boundaries on the p-chart.
d. Plot the sample proportions on the p-chart and connect them with straight lines.
e. Use pattern-analysis Rules 1-4 for detecting the presence of special causes of variation (Figure 13.22) to determine whether the process is out of control.

Transcribed Image Text:

Defectives 16 14 9. 14 12 11 8 12 16 17 13 15 16 13 10 9. 11 10 11 15 8 7 12 15 9 UCL UCL Centerline Centerline LCL LCL Rule 1: One point beyond Zone A Rule 2: Nine points in a row in Zone Cor beyond UCL UCL Centerline Centerline LCL LCL Rule 3: Six points in a row steadily increasing or decreasing Rule 4: Fourteen points in a row alternating up and down UCL A. UCL Centerline Centerline LCL LCL