To construct a p-chart, 20 samples of size 150 were drawn from a process. The proportion of defective items found in each of the samples is listed in the next table. Sample Proportion Defective Sample Proportion Defective 1 .03 11 .07 2 .05 12 .04 3 .10 13 .06 4 .02 14 .05 5 .08 15 .07 6 .09 16 .06 7 .08 17 .07 8 .05 18 .02 9 .07 19 .05 10 .06 20 .03

a. Calculate and plot the centerline and the upper and lower control limits for the p-chart.

b. Calculate and plot the A, B, and C zone boundaries on the p-chart.

c. Plot the sample proportions on the p-chart.

d. Is the process under control? Explain.

e. Should the control limits and centerline of part a be used to monitor future process output? Explain. Applying the Concepts—Basic