X-bar and R charts are maintained for an important quality characteristic (i.e., CTQ). The sample size is n=7; X-bar and R are computed for each sample. After 35 samples, we have found the average of X-bar = 7805 and the average of R = 1200.
Determine the UCL, CL, and LCL for the X-bar and R charts. You should show your justifications.
X-bar chart:
UCL =
CL =
LCL =
R chart:
UCL =
CL =
LCL =
Assuming that both charts exhibit control, estimate the process mean and standard deviation. Of course, your answers should be justified.
Process mean:
Process standard deviation:
If the quality characteristic (or CTQ) is normally distributed and if the specifications are 220