Use the following to answer Questions 15-16. The table includes summary of data concerning customer waiting times at Jim’s Electronics.
1) What is the D4 value associated with the R-chart?
2) Is the variation of this process under control?
A. Yes, the variation of the process is in control
B. No, the variation is out of control
C. Need to check if mean of the process is under control first
D. No, the sample size or subgroup must be 11 or more