What are the x-bar chart three sigma upper and lower control limits?
A)22 and 18
B)23.29 and 16.71
C)23.5 and 16.5
D)23.16 and 16.84
E)24 and 16

Question

Quizplus · Accepted Answer

In an x-bar chart, the three sigma upper and lower control limits are calculated using the formula:
Upper control limit = X-bar + 3(sigma/sqrt(n))
Lower control limit = X-bar - 3(sigma/sqrt(n))
Where X-bar is the sample mean, sigma is the sample standard deviation, and n is the sample size. Using the given data, we can calculate the sample mean (X-bar) as 20, the sample standard deviation (sigma) as 1.5, and the sample size (n) as 4. Substituting these values in the formula, we get:
Upper control limit = 20 + 3(1.5/sqrt(4)) = 23.16
Lower control limit = 20 - 3(1.5/sqrt(4)) = 16.84
Therefore, the three sigma upper and lower control limits are 23.16 and 16.84, respectively. The best choice is D.

What Are the X-Bar Chart Three Sigma Upper and Lower