Reconsider Exercise 8-5. Suppose that the quality characteristic is normally distributed with specification at 300 ± 40. What is the fallout level? Estimate Cp and Cpk and interpret these ratios.
Control charts for and R are to be set up for an important quality characteristic. The sample size is n = 4, and and r are computed for each of 25 preliminary samples. The summary data are
(a) Find trial control limits for and R charts.
(b) Assuming that the process is in control, estimate the process mean and standard deviation.