a)
To determine: The percentage spent in working, through observation
Introduction:
b)
To determine: The required sample size
Introduction: Sample size is required to determine the number of observations that are necessary to find the true cycle time.
c)
To determine: Whether the sample size taken by the assistant is adequate or not
Introduction: Sample size refers to the number of observations that are necessary to determine the cycle time. The major goal of sample size is to determine inferences about the population from the observations.
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Principles of Operations Management: Sustainability and Supply Chain Management (10th Edition)
- A time study analyst wants to estimate the time required to perform a certain job. A preliminary study yielded a mean of 6.4 minutes and a standard deviation of 2.1 minutes. The desired confidence is 95 percent. How many observations will he need (including those already taken) if the desired maximum error is:a. ± 10 percent of the sample mean?b. One-half minute?arrow_forwardFour samples of three observations each have been taken, with actual measurements (in centimetres) shown below. Construct three sigma mean and range charts, and determine if corrective action is needed. Sample 1 12.3 12.2 12.1 2 11.9 12.2 12.2 3 12.0 12.2 11.8 4 12.1 11.8 11.8arrow_forwardstandard time and work sampling 1.) How many stations should be open to minimize the cost? 2.) If the manager wants and error of not more than 6% at a 98% confidence level, how many observations must be made? 3.)arrow_forward
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- 3. Software upgrade times (in seconds) are being evaluated. Samples of five observations have been taken at each inspection and the results are listed. a. Using the factors from table below determine the lower and upper bounds for mean chart and draw the control chart by pointing the average of each inspection on the chart. Using the factors from table below determine the lower and upper bounds for range chart and draw the control chart by pointing the average of range for each inspection on the chart. 1st 3rd 4th 2nd Inspection Inspection Inspection Inspection 9,8 9,9 9,9 10,1 10,3 b. 1st sample 2nd sample 3rd sample 4th sample 5th sample Number of Observations in Sample, n 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 7 18 19 70 17 20 Factor for Chart, A₂ 1.88 1.02 0.73 0.58 0.48 0.42 0.37 0.34 0.31 0.29 0.27 0.25 0.24 0.22 0.21 0.20 0.19 0.19 0.18 10,2 10,3 9,7 9,9 9,8 Lower Control Limit, D₂ 0 0 0 0 0 FACTORS FOR R CHARTS 0.08 0.14 9,9 9,8 0.18 0.22 0.26 0.28 0.31 0.33 0.35 0.36 0.38 0.39…arrow_forwardPlease provide step-by-step solutionarrow_forward10arrow_forward
- Your twenty observations of Dr. Knowitall reveal the following information. Assume that the estimate is to be within 5 percent of the true proportion 96 percent of the time Activity Observed Number of Times Observed With patient 6 Reviewing test results 5 On phone 5 Idle 3 Away on emergency 1 Not available 1 Total 21 Calculate the sample size needed to estimate the proportion of time Dr. Knowitall spends away on emergencies.arrow_forwardAn analyst has been asked to prepare an estimate of the proportion of time that a turret lathe operator spends adjusting the machine, with 90% confidence level. Based on previous experience, the analyst believes the proportion will be approximately 30%. a. If the analyst uses sample size of 400 observations, what is the maximum error that will be associated with the estimate? b. What sample size would the analyst need in order to have the maximum error be no more than +/- 5%?arrow_forwarda) A machine is set to produce a diameter of 9 mm nominal, and a sample of five pieces is taken every hour, Table 3(a). Over the first 10 samples the following results were obtained; 1 2 3 4 5 6 8 9 10 Sample No. 9.05 9.05 9.04 9.04 9.06 9.06 9.04 9.06 9.05 9.03 9.03 9.04 9.05 9.04 9.04 9.04 9.07 9.03 9.05 9.06 9.03 9.06 9.04 9.04 9.05 9.05 9.06 9.03 9.05 9.04 9.04 9.04 9.06 9.05 9.05 9.04 9.06 9.04 9.06 9.05 9.06 9.05 9.04 9.04 9.06 9.04 9.05 9.05 9.05 9.03 Table 3(a) i. Calculate the control limits for this process ii. Graph the sample data for both the X-bar and R-bar charts. iii. Explain if this machine is adjusted and in control? From the information in Table 3(a), estimate the standard deviation of the process, ô . iv.arrow_forward
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