Six samples of five observations each have been taken and the results are listed below. Using the factors from the attached table 10-2, determine the upper and lower control limits for both of the X-bar and R charts,
79.20 80.50 79.60 78.90 80.50 79.70
78.80 78.70 79.60 79.40 79.60 80.60
80.00 81.00 80.40 79.70 80.40 80.50
78.40 80.40 80.30 79.40 80.80 80.00
81.00 80.10 80.80 80.60 78.80 81.10
X – BAR 79.48 80.14 80.14 79.60 80.02 80.38
RANGE 2.60 2.30 1.20 1.70 2.00 1.40
What is the X-bar LCL?
a. 81.04
b. 80.44
c. 78.88
d. 79.96
Expert Answer
From the given data, we have
https://d2vlcm61l7u1fs.cloudfront.net/media%2F1c5%2F1c5d6942-f348-4907-a3b1-602736718049%2FphpOwR5BY.png
So, the answer is Option C : LCL = 78.88