Question 4 [20 marks] By utilising Annexure A, answer the following questions: (a) 15 samples of...
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: Sample Mean Range Sample Mean Range 1 3.06 .42 4 3.13 .46 2 3.15 .49 5 3.06 .46 3 3.11 .41 6 3.09 .45 Factors for three-sigma control limits for x¯x¯ and R charts FACTORS FOR R CHARTS Number of Observations in Subgroup, n Factor for x¯x¯ Chart, A2 Lower...
Computer upgrades have a nominal time of 80 minutes. Samples of five observations each have been taken, and the results are as listed. SAMPLE 1 2 3 4 5 6 79.2 80.5 79.6 78.9 80.5 79.7 78.8 78.7 79.6 79.4 79.6 80.6 80.0 81.0 80.4 79.7 80.4 80.5 78.4 80.4 80.3 79.4 80.8 80.0 81.0 80.1 80.8 80.6 78.8 81.1 Factors for three-sigma control limits for x¯ and R charts FACTORS FOR R CHARTS Number of Observations in Subgroup, n...
The time to replace vehicle wiper blades at a service center was monitored using a mean and a range chart. Six samples of n = 20 observations have been obtained and the sample means and ranges computed: Sample Mean Range Sample Mean Range 1 3.06 .42 4 3.13 .46 2 3.15 .50 5 3.06 .46 3 3.11 .41 6 3.09 .45 Factors for three-sigma control limits for and R charts FACTORS FOR R CHARTS Number of Observations in Subgroup, n...
Problem 10-25 Resistors for electronic circuits are manufactured on a high-speed automated machine. The machine is set up to produce a large run of resistors of 1,000 ohms each. Use Exhibit 10.13. To set up the machine and to create a control chart to be used throughout the run, 15 samples were taken with four resistors in each sample. The complete list of samples and their measured values are as follows: Use three-sigma control limits READINGS (IN OHMS) 1014 1019...
Samples of n = 6 items each are taken from a process at regular intervals. A quality characteristic is measured, and x-bar and R values are calculated for each sample. After 50 samples, we have Compute control limits for the x-bar and R control charts. All points on both control charts fall between the control limits computed in part (a). What are the natural tolerance limits of the process? If the specification limits are 41 ± 5.0, what are your...
Samples ofn-6 items each are taken from a manufacturing process at regular intervals. A normally distributed quality characteristic is measured, and X and S values are calculated for each sample. After 50 samples, we have 50 50 X, = 1000 S,-75 and a) Compute the control limits for the Xand S control charts. b) Assume that all points on both control charts plot within the control limits computed in part (a). What are the natural tolerance limits of the process?...
Samples of n = 6 items are taken from a manufacturing process at regular intervals. A normally distributed quality characteristic is measured and ?̅ and S values are calculated for each sample. After 50 subgroups have been analyzed, we have : ∑ ?? ̅50 ?=1 = 1000 and ∑ ?? 50 ?=1 = 75 (a) Compute control limits for the ?̅ and S control charts. (b) Assume that all points on both charts plot within the control limits. What are...
54 A manufacturing process for the company producing wheel bearings was investigated Samples of 4 subgroups where tested each containing 6 wheel bearings The specification limits for the process are given as 40 and 5 2 Given the following data for random measurements taken on the wheel bearing dunng their three shifts 56 54 Subgroup 1 Subgroup 2 Subgroup 3 59 50 48 52 51 50 464258 52 57 50 543 56 47 | 49 Subgroup 4 55 51 50...
04)- 244+3-15 marás) Control charts for X and R are mairnt S marks) Contr ol charts for X and R are maintained for quality characteristic. The and R are computed for each sample. After 30 samples, the following a computed: 6690 R-1030 a- What are the tria Ilimits for the R chart ? tb) Assuming that the R chart is in control, what are the trial limits for the X char? Estimate the process mean and standard devintion. (d- Ifthe...
Twelve samples, each containing five parts, were taken from a process that produces steel rods at Emmanual Kodzi's factory. The length of each rod in the samples was determined. The results were tabulated and sample means and ranges were computed. The results were: SAMPLE SAMPLE MEAN (IN.) RANGE (IN.) SAMPLE SAMPLE MEAN (IN.) RANGE (IN.) 1 9.104 0.044 7 9.103 0.021 2 9.100 0.051 8 9.103 0.058 3 9.089 0.042 9 9.097 0.039 4 9.108 0.037 10 9.103 0.038 5...