Twenty-five samples of size 1000 each were drawn from a manufacturing process and the number of defectives in each sample was counted. The average sample proportion was 0.05. What would be the upper control limit for the p chart?
A) 0.0206
B) 0.0293
C) 0.0475
D) 0.0707

Question

Quizplus · Accepted Answer

The upper control limit (UCL) for a p-chart is calculated using the formula: UCL = p̄ + z * sqrt((p̄(1-p̄))/n), where p̄ is the average sample proportion, z is the z-value for the desired confidence level (typically 3 for 99.73% confidence), and n is the sample size. Here, p̄ = 0.05, n = 1000, and z = 3. Calculating gives UCL = 0.05 + 3 * sqrt((0.05 * 0.95) / 1000) = 0.0707.

Twenty-Five Samples of Size 1000 Each Were Drawn from a Manufacturing