Random samples of four items are selected from a manufacturing process at regular intervals and a certain quality characteristic is measured. After 25 samples,ΣX = 15,350 and ΣR = 411.4. To construct a mean chart,what is the value for R-bar used to compute the limits?
A)411.4
B)614
C)16.46
D)102.88

Question

Quizplus · Accepted Answer

To construct the mean chart, we need to use the average range (R-bar) to compute the control limits. R-bar is calculated using the formula R-bar = ΣR/n, where n is the number of samples (25 in this case). Substituting the given values, we get R-bar = 411.4/25 = 16.46. Therefore, the correct answer is C. Option A is incorrect because ΣR is the sum of the range for 25 samples, not the average range. Option B is incorrect because it does not use any formula or information given in the question. Option D is incorrect because it does not use the correct formula to compute R-bar.

Random Samples of Four Items Are Selected from a Manufacturing