P-chart and c-chart. Using the appropriate control chart, determine two-sigma control limits for each Problem case, a. An inspector found an average of 3.9 scratches in the exterior paint of each of the automobiles being prepared for shipment to dealers. b. Before shipping lawnmowers to dealers, an inspector attempts to start each mower and notes any that do not start on the first try. The lot size is 100 mowers, and an average of 4 did not start (4 percent).

answer only if you can answer both.

Why is it important to prove that a process is proven capable before developing statistical control limits (i.e., SPC charts)?

McDaniel Shipyards wants to develop control charts to assess the quality of its steel plate. They take ten sheets of 1" steel plate and compute the number of cosmetic flaws on each roll. Each sheet is 20' by 100'. Based on the following data, develop limits for the control chart, plot the control chart, and determine whether the process is in control. ​ Sheet Number of    flaws 1 1 2 1 3 2 4 0 5 1 6 5 7 0 8 2 9 0 10 2

Inter-State Moving and Storage Company wishes to establish a control chart to monitor the proportion of residential moves that result in written complaints due to late delivery, lost items, or damaged items. A sample of 40 moves is selected for each of the last 12 months. The number of written complaints in each sample is 9, 7, 4, 9, 1, 9, 11, 5, 5, 8, 7, and 15. Number Defective Percent defective 9 18 7 14 4 8 9 18 1 2 9 18 11 22 5 10 5 10 8 16 7 14 15 30 a. Insert the mean proportion defective, UCL, and LCL. (Leave no cells blank - be certain to enter "0" wherever required. Round your intermediate calculations and final answers to 2 decimal places.) Mean proportion defective   UCL   LCL   c. Does it appear that the number of complaints is out of control for any of the months?multiple choice Yes No

Administering new bank accounts is intended to average 15 minutes each. Five samples of four observations each have been taken. Use the sample data in concurrence with Table 2.3 to create upper and lower control limits for both a mean chart and a range chart. Do results propose that the procedure is in control?   Sample 1 Sample 2 Sample 3 Sample 4 Sample 5   11.2 11.3 10.7 10.9 10.8   10.9 10.8 10.9 11.3 11.2   10.8 10.9 10.9 11.1 11.3   11.1 11.4 11.1 11.5 10.7 Total: 44 44.4 43.6 44.8 44

4) Because a telephone customer service center has experienced several problems, it has begun to analyze the data from customer complaints. The first step was to construct the following table. Use this data to build a Pareto chart to help identify the "vital few" problems. Process Failure Total Failures Person not available Incorrect information given Phone line busy Long delay Phone tree confusing People unfriendly 12 39 20 17 DFocus e

Checkout time at a supermarket is monitored using a mean and a range chart. Six samples of n = 20 observations have been obtained and the sample means and ranges computed:

1. The overall average on a process you are attempting to monitor is 55.0 units. The process population standard deviation is 1.84. Sample size is given to be 16. ​a) Determine the ​3-sigma x​-chart control limits.   Upper Control Limit ​(UCLx​)=56.3856.38 units ​(round your response to two decimal​ places). Lower Control Limit ​(LCLx​)=53.6253.62 units ​(round your response to two decimal​ places). ​b) Now determine the ​2-sigma x​-chart control limits.   Upper Control Limit ​(UCLx​)=? units ​(round your response to two decimal​ places).       2.  Sample ​Size, n Mean​ Factor, A2 Upper​ Range, D4 Lower​ Range, D3 2 1.880 3.268 0 3 1.023 2.574 0 4 0.729 2.282 0 5 0.577 2.115 0 6 0.483 2.004 0 7 0.419 1.924 0.076 8 0.373 1.864 0.136 9 0.337 1.816 0.184 10 0.308 1.777 0.223 12 0.266 1.716 0.284 ​Thirty-five samples of size 7 each were taken from a​…

Use the three-step process described in the previous section on Using Control Charts and RunsTests Together to decide if the following observations represent a process that is in control.Observation 1 2 3 4 5 6 7 8 9 10 11 12No. of errors 1 0 3 2 0 1 3 2 1 0 2 3