Concept explainers
i)
Interpretation: by using
Concept introduction:Mean(x-bar) charts:
X bar charts is a type of statistical process control chart which measures a central a shift in the central tendency of the process. In other words, X- bar charts monitor the mean or average of a product characteristics. The central line of the X-bar chart is the average of the samples and limits are defined as
Upper control limit
Lower control limit
(
Abbreviations:
R chart:
R-chart or range-chart is also a type of statistical process control chart, but it monitors the range of dispersion or variability of process. The central line of the r- chart is the average range and limits are:
(
The data corresponding to sampling of the given firm is given below
Mean of the diameter
Average range
Control limits are
ii)
Interpretation: by using
Concept introduction:a process is said to be out control if one or more data points fall outside the control limits.
iii)
Interpretation: determine what trade off would consider by using result of a and b.
Concept introduction: trade off is a situational decision that involves diminishing or losing one quality, quantity or design in return for gains in other aspects
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Operations Management: Processes and Supply Chains (12th Edition) (What's New in Operations Management)
- At Quick Car Wash, the wash process is advertised to take less than 7 minutes. Consequently, management has set a target average of 390 seconds for the wash process. Suppose the average range for a sample of 9 cars is 8 seconds. Use the accompanying table to establish control limits for sample means and ranges for the car wash process. LOADING... Click the icon to view the table of factors for calculating three-sigma limits for the x overbarx-chart and R-chart. Factors for calculating three-sigma limits for the x overbarx-chart and R-chart Size of Sample (n) Factor for UCL and LCL for x overbarx-chart (Upper A 2A2) Factor for LCL for R-Chart (Upper D 3D3) Factor for UCL for R-Chart (Upper D 4D4) 2 1.8801.880 00 3.2673.267 3 1.0231.023 00 2.5752.575 4 0.7290.729 00 2.2822.282 5 0.5770.577 00 2.1152.115 6 0.4830.483 00 2.0042.004 7 0.4190.419 0.0760.076 1.9241.924 8 0.3730.373…arrow_forwardAt Quick Car Wash, the wash process is advertised to take less than 7 minutes. Consequently, management has set a target average of 390 seconds for the wash process. Suppose the average range for a sample of 9 cars is 8 seconds. Use the accompanying table to establish control limits for sample means and ranges for the car wash process. LOADING... Click the icon to view the table of factors for calculating three-sigma limits for the x overbarx-chart and R-chart. Factors for calculating three-sigma limits for the x overbarx-chart and R-chart Size of Sample (n) Factor for UCL and LCL for x overbarx-chart (Upper A 2A2) Factor for LCL for R-Chart (Upper D 3D3) Factor for UCL for R-Chart (Upper D 4D4) 2 1.8801.880 00 3.2673.267 3 1.0231.023 00 2.5752.575 4 0.7290.729 00 2.2822.282 5 0.5770.577 00 2.1152.115 6 0.4830.483 00 2.0042.004 7 0.4190.419 0.0760.076 1.9241.924 8 0.3730.373…arrow_forwardThe Watson Electric Company produces incandescent light bulbs. The following data on the number oflumens for 40-watt light bulbs were collected when the process was in control. a. Calculate control limits for an R-chart and an x-chart.b. Since these data were collected, some new employees were hired. A new sample obtained the following readings: 625, 592, 612, and 635. Is the process still in control?arrow_forward
- A can filling process at a beverage manufacturing factory is assumed to be in control with limits of 89 plus/minus 4 had sample averages for the x-bar chart of the following : 87.1, 87, 87.2, 89, 90, 88.5, 89.5 and 88. Which of the following statement below are correct? a. None is correct b. Not enough information to determine c. Process mean is out -of-control d . Process mean is NOT out-of-controlarrow_forwardSam’s Long Life 60-watt light bulbs are designed to have a life of 1,350 hours with tolerance of ± 340 hours. A recent representative sample from the process that makes these light bulbs revealed a mean of 1,290 hours, with a standard deviation of 94 hours. Compute a. Compute the process capability ratio and the process capability index, and comment on the overall capability of the process b. Explain to what extent the process for producing Sam’s Long Life 60-watt light bulbs would have to be improved to achieve 4-sigma quality. c. show detail workarrow_forwardAt Quick Car Wash, the wash process is advertised to take less than 6 minutes. Consequently, management has set a target average of 320 seconds for the wash process. Suppose the average range for a sample of 10 cars is 10 seconds. Use the accompanying table to establish control limits for sample means and ranges for the car wash process.arrow_forward
- The Watson Electric Company produces incandescent light bulbs. The following data on the number of lumens for 40-watt light bulbs were collected when the process was in control. The standard deviation of the process is 15. Calculate control limits for an x-bar chart with 3-sigma limit and draw the chart. Since these data were collected, some new employees were hired. A new sample obtained the following readings: 625, 592, 612, and 650. Is the process still in control?arrow_forwardYou work for Raider Data Systems where thousands of insurance records are entered by clerks each day for a variety of client firms. You are in charge of setting control limits to include 99.73% of the random variation in the data entry process when it is in control. Samples that you collected from 20 employees are shown below. You carefully examine 100 records entered by each employee and count the number of errors entered by each clerk. You also compute the proportion defective in each sample. Using a p-chart, what are the upper and lower control limits? Sample Errors Made Proportion Defective 1 4 0.04 2 5 0.05 3 6 0.06 4 3 0.03 5 8 0.08arrow_forwardA quality inspector took five samples in five hours, each with four observations, of the length time for glue to dry. The analyst compute the mean of each sample and the computed the grand mean. All values are in minutes. Use this information to obtain three-sigma control limits for means. It is known from previous experience that the standard deviation of the process is 0.02 minutes. Draw a control chart Please provide a step-by-step solutionarrow_forward
- Analysis of the output of a process has suggested that the variability is nonrandom on several occasions recently. However, each time an investigation has not revealed any assignable causes. What are some of the possible explanations for not finding any causes? What should the manager do? And Use the dimensions of quality to describe typical characteristics of these products and services such as a. A television set. b. Eating a meal in a restaurantarrow_forwardSteps to monitor using the control charts: Now monitor the process. An additional ten days of data have been collected, see table labeled “1st 10 Days of Monitoring Reservation Processing Time” in the Data File. Develop Xbar and R charts for the 1st 10 days of monitoring. Plot the data for the 1st 10 days on the Xbar and R charts. Is the process in control? If the control chart indicates an out-of-control process, note which days, the pattern, and whether it is the Xbar or R chart. Now that we have set up the control charts using enough data from a stable process, the 30 days of data, we will monitor the process. While monitoring the process, what will we use as the upper control limit for the X-bar Chart to compare against our new x-bar values? Enter your response to three decimal places. You do not need to include the units (minutes), ONLY the numeric value. USE DATA TO GET UPPER CONTROL LIMITarrow_forwardAt Quick Car Wash, the wash process is advertised to take less than 7 minutes. Consequently, management has set a target average of 390 seconds for the wash process. Suppose the average range for a sample of 10 cars is 11 seconds. Use the accompanying table to establish control limits for sample means and ranges for the car wash process. The UCL Subscript x overbar equals seconds and the LCL Subscript x overbar equals seconds. (Enter your responses rounded to two decimal places.)arrow_forward
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