Historically, the average proportion of defective bars has been 0.015. Samples will be of 100 bars each. Construct a p-chart using z = 3. What is the value of UCL?
A) less than or equal to 0.050
B) greater than 0.050 but less than or equal to 0.060
C) greater than 0.060 but less than or equal to 0.070
D) greater than 0.070

Question

Quizplus · Accepted Answer

The Upper Control Limit (UCL) for a p-chart is calculated using the formula UCL = p + z * sqrt[(p(1-p))/n], where p is the average proportion of defects, z is the z-value corresponding to the desired confidence level, and n is the sample size. Substituting the given values (p = 0.015, z = 3, n = 100) into the formula gives UCL = 0.015 + 3 * sqrt[(0.015 * 0.985)/100] ≈ 0.015 + 0.036 = 0.051, which falls into the range greater than 0.050 but less than or equal to 0.060.

Historically, the Average Proportion of Defective Bars Has Been 0