A machined part has a lower specification limit of 3.5 inches and an upper specification limit of 3.9 inches.The range for the pre-control green zone is:
A)3.6 inches to 3.8 inches.
B)3.8 inches to 3.9 inches.
C)less than 3.5 inches.
D)3.5 inches to 3.9 inches.

Question

Quizplus · Accepted Answer

The pre-control green zone is defined as the range within which 99.7% of the parts are expected to fall. This corresponds to a range of ± 3 standard deviations from the mean. Assuming the mean is at the center of the specification limits (3.7 inches), this corresponds to a range of 3.6 inches to 3.8 inches, which is option A.

A Machined Part Has a Lower Specification Limit of 3