Question: 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 x‾ and s charts.
c) If the process mean shifts to 22, what is the probability of concluding that the process is still in control?