TABLE 7-3 The Lifetimes of a Certain Brand of Light Bulbs Are

question 118

Essay

TABLE 7-3
The lifetimes of a certain brand of light bulbs are known to be normally distributed with a mean of 1,600 hours and a standard deviation of 400 hours. A random sample of 64 of these light bulbs is taken.
-Referring to Table 7-3, the probability is 0.20 that the sample mean lifetime differs from the population mean lifetime by at least how many hours?

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Definitions:

Visual Fields

The range of vision that can be seen without moving the eyes.

Auditory Tube

Also known as the Eustachian tube, it connects the middle ear to the nasopharynx and helps equalize pressure in the middle ear.

Middle Ear

Air-filled space within the temporal bone; contains auditory ossicles; between the external and internal ear.

Sound Waves

Vibrations that travel through the air or another medium and can be heard when they reach a person's or animal's ear.