Twenty Samples of Size 8 Were Taken from a Stable

Multiple Choice

Twenty samples of size 8 were taken from a stable process.From past studies of the process,you know that the overall mean is 42.5 and that the average of the samples range is 2.0.What is the upper control limit for the x-bar chart? Use the information contained in the attached chart to determine your answer.

A) 43.25
B) 44.50
C) 46.22
D) 48.50