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:

Gantt Charts

Visual project management tools that display tasks or activities against time, often used for planning and scheduling.

Business Documents

Written records that are essential for the operation and management of a business, such as contracts, financial statements, and memos.

Organization Chart

A chart depicting the roles, divisions, or duties within an organization and how they relate to each other.

Flowchart

Process diagram that illustrates a sequence of events from start to finish.