A Design Engineer Wants to Construct a Sample Mean Chart

question 26

Multiple Choice

A design engineer wants to construct a sample mean chart for controlling the service life of one of the types of light bulbs 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 bulbs,with these results: What is the standard deviation of the sampling distribution of sample means?

• A)5 hours
• B)6.67 hours
• C)10 hours
• D)11.55 hours
• E)20 hours

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Definitions:

Hydroxyapatite

A naturally occurring mineral form of calcium apatite, mainly found in bones and teeth, providing hardness and strength.

Osteocyte

Mature bone cell surrounded by bone matrix.

Bone Maintenance

The process by which bone tissue is renewed through the activities of osteoclasts (breaking down bone) and osteoblasts (forming new bone), ensuring strength and health of bones.

Lamellar Bone

The mature type of bone tissue that forms concentric layers or sheets, providing strength and stability.