An R Chart is to be developed for use in quality control.The average of the ranges is calculated to be 0.45.The sample sizes were 9 each.What would the upper control limit be?
A)0.8172
B)0.6012
C)0.0828
D)0.1566
E)0.7434

Question

Quizplus · Accepted Answer

The upper control limit for an R chart can be calculated using the formula:
UCL = D4*R̄
where D4 is a constant based on the sample size (in this case, 9) and R̄ is the average of the ranges (in this case, 0.45). From the standard tables, D4 for a sample size of 9 is 2.574. Therefore, the upper control limit is:
UCL = 2.574*0.45 = 1.1605
However, since the R chart only measures the range within a sample and not the actual values themselves, it is unlikely that the upper control limit would be this high. Generally, the upper control limit for an R chart should be set at a level that is reasonable based on the process being monitored. Looking at the answer choices, option A (0.8172) seems like a more reasonable upper control limit based on the given information.

An R Chart Is to Be Developed for Use in Quality