A manufacturer purchases small bolts in cartons that usually contain several thousand bolts. Each shipment consists of a number of cartons. As part of the acceptance procedure for these bolts, 400 bolts are selected at random from each carton and are subjected to visual inspection for certain non-conformities. In a shipment of 10 cartons, the respective percentages of rejected bolts in the samples from each carton are 0, 0, 0.5, 0.75, 0,2.0, 0.25, 0, 0.25, and 1.25. Required:
a. What are the limits for this process?
b. What does the centerline represent with respect to data shown?
c. Does this shipment of bolts appear to exhibit statistical control with respect to the quality characteristics examined in this inspection?
d. What the np chart limits for this problem and what do you conclude on statistical control?