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1. Which of the following statements is INCORRECT regarding process variations?

ID: 343717 • Letter: 1

Question

1. Which of the following statements is INCORRECT regarding process variations?

Assignable variations can be reduced and eliminated.

Common variation is inevitable.

A process under statistical control is a process with zero variation.

It is impossible to have zero variation in production processes.

2.

An activity in a PERT network has these time estimates: optimistic = 2, most likely = 5, and pessimistic = 8. The variance of the activity time is:

1.00

0.50

0.25

1.21

3.

Suppose you are asked to determine the Lower Control Limit for a p-chart for quality control purposes. Samples are taken from the production line. The fraction defective is 0.03 and the standard deviation is 0.006 based on the samples. Set z = 3. Which of the following is the LCL of the p-chart?

0.012

0.048

0.006

0.013

Assignable variations can be reduced and eliminated.

Common variation is inevitable.

A process under statistical control is a process with zero variation.

It is impossible to have zero variation in production processes.

Explanation / Answer

1. The correct Answer is "A process under statistical control is a process with zero variation."

In any production process, regardless of how well designed or carefully maintained it is, a certain amount variability will always exist. The best we can do is to reduce it however we can not make it zero.