BooksCDs.com sells books, videos, DVDs, and CDs through its Internet Website. The company ships thousands of orders each day from seven national distribution centers. BooksCDs.com wants to establish a p-chart to monitor the quality of its distribution process, specifically the number of "problem" orders. A problem order is one that is delivered to a customer late (i.e., after five days), incorrect or incomplete. The company sampled 500 orders every other day for 20 samples and tracked them to final customer delivery, the results of which are as follows:
Sample (First Number 1-20) Number of Problem Orders (Second Number 14,22,36,17, etc.)
1, 14 11, 38
2, 22 12, 24
3, 36 13, 15
4 ,17 14, 12
5, 25 15, 10
6, 41 16, 16
7, 18 17, 9
8, 19 18, 21
9, 26 19, 18
10, 28 20, 12
Construct a p-chart with 3σ limits for invoice errors and indicate if the process was out of control at any time. Round your answer to 3 decimal places.
1. What is the average percent of problem orders?
2. What is the 3σ upper control limit?