A Design Engineer Wants to Construct a Sample Mean Chart

question 15

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: $$\begin{array} { r } { \text { Service Life (hours) } }\\\begin{array} { l l l l l } \text { Sample } & \\\hline 1 & 495 & 500 & 505 & 500 \\2 & 525 & 515 & 505 & 515 \\3 & 470 & 480 & 460 & 470\end{array}\end{array}$$ 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?

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Definitions:

Trade Name

A term that is used to indicate part or all of a business’s name and that is directly related to the business’s reputation and goodwill. Trade names are protected under the common law (and under trademark law, if the name is the same as the firm’s trademark).

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The official legal name under which a company operates and is recognized.

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Distinctive Trademarks

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