8 10 6 4 5 7 8 12 8 15

14 10 10 7 5 8 6 10 4 8

a. What is an estimate of the proportion defective for the piston manufacturing process when it is control?

b. Construct a p chart for the manufacturing process, assuming each sample has 200 pistons.

c. With the results of part (b), what conclusion should be drawn if a sample of 200 has 20 defective pistons?

d. Compute the upper and lower control limits for an np char.

e. Answer part (c) using the results of part (d).