A Design Engineer Wants to Construct a Sample Mean Chart

question 118

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: $$\begin{array} { r } { \text { Service Life (hours) } }\\\begin{array} { l l l l l } \text { Sample } & \\\hline 1 & 495 & 500 & 505 & 500 \\2 & 525 & 515 & 505 & 515 \\3 & 470 & 480 & 460 & 470\end{array}\end{array}$$ What is the mean of the sampling distribution of sample means when service life is in control?

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Definitions:

Epidermis

The outermost layer of skin that provides a waterproof barrier and creates our skin tone.

Psoriasis

A chronic skin condition characterized by red patches covered with silver-white scales.

Protein Substance

A type of biological molecule composed of one or more chains of amino acids, critical for the structure, function, and regulation of the body's tissues and organs.

Scar

The fibrous tissue that replaces normal skin after an injury or surgical incision as part of the healing process.