A Design Engineer Wants to Construct a Sample Mean Chart

question 69

Multiple Choice

A design engineer wants to construct a sample mean chart for controlling the service life of a halogen headlamp his company produces. He knows from numerous previous samples that this service life is normally distributed with a mean of 500 hours and a standard deviation of 20 hours. On three recent production batches, he tested service life on random samples of four headlamps, with these results

If he uses upper and lower control limits of 520 and 480 hours, on what sample(s) (if any) does service life appear to be out of control?

• A)sample 1
• B)sample 2
• C)sample 3
• D)both samples 2 and 3
• E)all samples are in control

---

Definitions:

Margin of Error

An expression of the amount of random sampling error in a survey's results, indicating a range within which the true value likely falls.

Degree of Confidence

Another term for confidence level, indicating the statistical probability that a parameter lies within a specified range.

Conservative Party

A political party espousing the values of conservatism, focusing on tradition, stability, and free market principles.

Confidence Interval

An estimated range based on sample data within which a population parameter is expected to lie, with a given degree of certainty.