Concept explainers
a)
To determine: The type of control charts to be used to monitor the process.
Introduction: Statistical process control is the method that helps to measure and control the quality during the process of production.
b)
To determine: The 3-sigma control limits for the process.
Introduction: Statistical process control is the method that helps to measure and control the quality during the process of production.
c)
To determine: Whether the process is in control.
Introduction: Statistical process control is the method that helps to measure and control the quality during the process of production.
d)
To determine: The 3-sigma control chart and whether the process is in control.
Introduction: Statistical process control is the method that helps to measure and control the quality during the process of production.
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Chapter 6 Solutions
Operations Management
- One of New England Air's top competitive priorities is on-time arrivals. Quality VP Clair Bond decided to personally monitor New England Air's performance. Each week for the past 30 weeks, Bond checked a random sample of 100 flight arrivals for on-time performance. Sample (week) Late Flights Sample (week) Late Flights1 3 16 32 3 17 23 11 18 64 2 19 35 1 20 26 2 21 17 5 22 228 7 23 39 11 24 110 0 25 211 3 26 112 5 27 013 2 28 114 2 29 415 7 30 5 a) The overall fraction of late flights is [ 0.04 ] enter your response here (enter your response as a real number rounded to two decimal places.) Using a 95% confidence level, the upper and lower control limits are: Upper control limit (UCLp)= enter your response here [ ? ] (enter your response as a fraction between 0 and 1, rounded to four decimal places) Lower control limit (LCLp) =…arrow_forwardA process that is considered to be in control measures an ingredient in ounces. Below are the last 10 samples (each of size 11 = 5) taken. The population process standard deviation, a) What is u;:?b) If::: = 3, what are the control limits for the mean chart?c) What are the control limits for the range chart?d) Is the process in control?arrow_forwardMcDaniel 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 2arrow_forward
- Why are most processes not in statistical control whenthey are first sampled for control chart purposes?arrow_forwardWhat is it important to prove that a process is proven capable before developing statistical control limit ?arrow_forwardSelect three service companies or organizations you arefamiliar with and indicate how process control charts couldbe used in each.arrow_forward
- An automatic filling machine is used to fill 1-liter bottles of cola. The machine’s output is approximately normal with a mean of 1.0 liter and standard deviation of .01 liter. Output is monitored using means of samples of 25 observations. Determine upper and lower control limits that will include roughly 97% of the sample means when the process is in control. Using Appendix B, Table A to find the value of Z corresponding to the mean control limits.arrow_forwardUse 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 3arrow_forwardWhy is it important to prove that a process is proven capable before developing statistical control limits (i.e., SPC charts)?arrow_forward
- A hospital manager receives a certain number of complaints each day about the hospitals service. Complaints for 15 days are given in the table shown. What are the control limits when one will construct a control chart using three sigma limits? Days Number of Complaints 1 4 2 6 3 4 4 5 5 4 6 8 7 6 8 7 9 5 10 3 11 5 12 4 13 4 14 6 15 4arrow_forwardA teller at a drive-up window at a bank had the following service times (in minutes) for 20 randomly selected customers: SAMPLE 1 2 3 4 4.5 4.6 4.5 4.7 4.2 4.5 4.6 4.6 4.2 4.4 4.4 4.8 4.3 4.7 4.4 4.5 4.3 4.3 4.6 4.9 a. Determine the mean of each sample. b. If the process parameters are unknown, estimate its mean and standard deviation. c. Construct control charts for means and ranges using Table 10.3. Are any samples beyond the control limits? If so, which one(s)? d. If the process has a known mean of 4.4 and a known standard deviation of .18, what would three-sigma control limits be for a mean chart? Are any sample means beyond the control limits? If so, which one(s)?arrow_forwardWhat trade-offs are involved in each of these decisions?a. Deciding whether to use two-sigma or three-sigma control limits.b. Choosing between a large sample size and a smaller sample size.c. Trying to increase the capability of a process that is barely capable.arrow_forward
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