21-37 true or false please The standard deviation all (population) should be equ

Question

21-37 true or false please

The standard deviation all (population) should be equal to the standard deviation of the sample 22 T F As the sample size n' increases the distance between the control limits will 23 T F The central tendency of all data distribution can be estimawed by the grand mean of 24 T F SPC methods can be applied to direct variable measurements. but not to artribute 25 T F X-bar and R control chart is used to determine if the average delects in a process that has changed by a special cause 26 T F The range of a process data can also be defined as upper specification limi minus lower 27 T F An external customer is the end user of the company product or service 2s T F Special cause variation in a control chart identified by anything beyond of the variation in the sam 29 T F In a charting process, control limits occur at the mean 3 standard deviations of Population data. 30 T F Control chart centerlines are computed using grand average 31 T F Pre centrol method can be used when all assignable causes are eliminated the process is in control, and found capable F p-chart is a variable control chart used to check the fraction of the defective parts. 32 T T F The chart is easier to use than p-chart 33 T F Individual charts are always more sensitive to process changes than x-bar charts 35 T F The lerm defect and defective does not mean same thing in a product 36 T F If MR-chart is out of control, then X-Individual chart is not valid. 37 T F Walter Schewhart developed control limit formulas for both variable and attribute charts ihn imply contry)

Explanation / Answer

21. False. Because the population std.deviation may not be equal to the sample std.deviation most of the times due to errors in the selection of samples, effect of extreme values of population, etc,. We need to find the value that is as much as close to the population std.deviation as the finding of exact value is not possible most of the times. Hence, the given statement is False.

22. True. When we increase the sample size, n then we observe that the distance between cotrol limits has decreased. At 5 samples, the UCL and LCL are 100 and 50 respectively, then at 20 samples, the control limits come closer, that is, less wider than that of 5 samples, say at 20 samples, the UCL and LCL are 80 and 60 respectively.

23. True only when such central tendency is population mean but not other measures such as median or mode or others. You can check this by creating various examples. Say a population with 1 to 15, that is, 1,2,3,......,14,15. Divide this into 3 samples. First 1 to 5 whose mean is 3; Second sample is 6 to 10 which has mean of 8 and 3rd sample is 11 to 15 where we get mean of 13. Now, calculate grand mean of these 3 sample means which is 8 (since, 24÷3) and then compare it with population mean, that is, Add 1 to 15 & divide by 15, you will get 8. Hence, the given statement is true.

24. False. Because SPC(Statistical Process Control) Methods can be applied to both variable and attribute values. Thus, it is False.

35. True. Defect means there is some problem within the product but not the whole product is defective where as the term defective means the entire product itself has the defect. Hence, we say there is some defect in the product and the product is defective. We say the product has some defect or defects and it is a dective product. If it has defect, we have to repair to make it good but if it is defective, we need to replace the defective one with a good one. Hence, True.

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