Sixty samples of size 600 each were drawn from a manufacturing process and the number of defectives in each sample was counted. The average sample proportion was 0.04. What would be the lower control limit for the p chart?
A) 0.008
B) 0.016
C) 0.048
D) 0.064

Question

Quizplus · Accepted Answer

To find the lower control limit for the p chart, we use the formula: LCL= p̅-3√(p̅(1-p̅)/n)
where p̅ is the average sample proportion and n is the sample size.
LCL=0.04-3√(0.04*0.96/600)
LCL=0.04-0.016
LCL=0.024
Therefore, the lower control limit for the p chart is 0.024, which is closest to option B (0.016).

Sixty Samples of Size 600 Each Were Drawn from a Manufacturing