Random samples of 4 items are selected from a manufacturing process at regular intervals and a certain quality characteristic is measured. After 25 samples, $\Sigma$ X = 15,350 and $\Sigma$ R = 411.4
To construct a mean chart, what is the lower control limit (LCL) for the mean?
A) 602.004
B) 411.400
C) 625.666
D) 0.00

Question

Quizplus · Accepted Answer

The LCL for the mean chart is calculated using the formula: LCL = $\bar{X}$ - A2 * $\bar{R}$. Here, $\bar{X}$ = $\Sigma$ X / n = 15,350 / 25 = 614, $\bar{R}$ = $\Sigma$ R / 25 = 16.456, and A2 for n=4 is 0.729. Thus, LCL = 614 - (0.729 * 16.456) = 602.004.

Random Samples of 4 Items Are Selected from a Manufacturing Σ\SigmaΣ

Random Samples of 4 Items Are Selected from a Manufacturing $\Sigma$