Nels Neugent,Purchasing Manager at Mid-West Medical Center,is designing a p chart to monitor the proportion of defective purchase orders issued at Mid-West.He has the proportions defective for 22 samples of purchase orders.Each sample contains 150 purchase orders,and the average proportion defective is 0.08. The centerline for Nels's p chart is ___________.
A) 0.08
B) 75
C) 22
D) 1.76
E) 0.008

Question

Quizplus · Accepted Answer

The centerline for a p chart is calculated as the overall proportion defective. 
Overall Proportion Defective = (Total Number of Defectives) / (Total Number of Purchase Orders)
In this case, we are given the average proportion defective for 22 samples of purchase orders. 
Total Number of Defectives = Average Proportion Defective * Total Number of Purchase Orders
Total Number of Purchase Orders = Sample Size * Number of Samples
Plugging in the given values, we get:
Total Number of Purchase Orders = 22 * 150 = 3300
Total Number of Defectives = 0.08 * 3300 = 264
Overall Proportion Defective = Total Number of Defectives / Total Number of Purchase Orders = 264 / 3300 = 0.08
Therefore, the centerline for Nels's p chart is 0.08, which is option A.

Nels Neugent,Purchasing Manager at Mid-West Medical Center,is Designing a P