The Lifetimes of Projector Bulbs of a Particular Type Are

question 30

Short Answer

The lifetimes of projector bulbs of a particular type are normally distributed with a mean of 470 hours and a standard deviation of 15 hours. What percentage of the bulbs has lifetimes that lie within 2 standard deviations of the mean on either side?

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Definitions:

Normal Distribution

A bell-shaped frequency distribution curve, where most occurrences take place in the middle of the distribution and taper off symmetrically towards either end.

Test Statistic

A standardized value used in hypothesis testing to determine whether to reject the null hypothesis.

Viewing Time

The duration or amount of time spent looking at, engaging with, or observing something, such as a screen, artwork, or event.

National Average

The mean value calculated from data points collected across a nation, often used in reference to economic, educational, or health indicators.