Question: 1. Suppose that you collect data for 15 samples of 30 units each, and find that on average, 2.5 percent of the products are defective. What are the UCL and LCL for this process?
2. Peerless Windows is a major manufacturer and installer of windows into new homes. Currently, management has found that it has experienced a large number (about 15% of all orders placed) of customer claims against Peerless. These customers, often builders, are claiming that they are receiving shipments of windows that are built to the wrong specifications. Correcting these errors has cost Peerless a great deal in terms of time, resources, and disrupted schedules. To determine if the order entry process is at fault, management has collected orders from the last two years. For each month, 100 orders were withdrawn and reviewed. The results are summarized in the table below. Experience with this product has resulted in the mean defect rate being 7.5 with the LCL being 0 and the UCL being 15. As an analyst, you have been asked to review the order entry process with the goal of assessing whether this process is causing the problems.
