ASQ Certified Quality Engineer (CQE) — Question 8

An X-bar and R chart was prepared for an operation using twenty samples with five pieces in each sample; X-bar was found to be 33.6 and R-bar was 6.20.
During production, a sample of five was taken and the pieces measured 36, 43, 37, 25, and 38. At the time, this sample was taken:

Answer options

• A. Both the average and range were within control limits.
• B. Neither the average nor range were within control limits.
• C. Only the average was outside control limits.
• D. Only the range was outside control limits. D

Correct answer:

Explanation

To determine if the average and range are within control limits, we need to calculate the average and range of the new sample. The average of the new sample is 35.8, which is outside the control limit of 33.6, while the range is 18, which is outside the control limit of 6.20. Therefore, the correct answer is B, as both the average and range are outside the control limits.