Assignment:
A quality analyst wants to construct a control chart for determining whether four machines, all producing the same product, are under control with regard to a particular quality attribute. Accordingly, she inspected 1,000 units of output from each machine in random samples, with the following results: Machine, Total Defects 1,23 2,15 3,29 4,13 What are the control chart upper and lower control limits for z = 2?