Samples of size n = 5 are collected from a process every half hour. After 50 samples have been collected, we calculate. x = 20.0 and s 1.5. Assume that both charts exhibit control and that the quality characteristic is normally distributed.
(a) Estimate the process standard deviation.
(b) Find the control limits on the charts.
(c) If the process mean shifts to 22, what is the probability of concluding that the process is still in control?