Question

1) If a sample of items is taken and the mean of the sample is outside the control limits, the process is: A) in control, but not capable of producing within the established control limits. B) within the established control limits with only natural causes of variation. C) likely out of control and the cause should be investigated. D) monitored closely to see if the next sample mean will also fall outside the control limits. E) producing high quality products.

Answer 1

Answer: The process is likely out of control and the cause should be investigated.

Explanation: In statistical quality control, there are to points to keep the process in check. The LCL( Lower control limit) and the UCL(Upper Control limit). These two points are a range which enables the quality controller to know that the point is still within the control limits. But once the mean is outside the sample, the process is deemed "out of control" and steps are taken to know the cause and brought back within the limits.