The Expected (Mean)life of a Particular Type of Light Bulb

question 10

Multiple Choice

The expected (mean) life of a particular type of light bulb is 1,000 hours with a standard deviation of 50 hours. The life of this bulb is normally distributed. What is the probability that a randomly selected bulb would last longer than 1150 hours?

• A) 0.4987
• B) 0.9987
• C) 0.0013
• D) 0.5013
• E) 0.5513

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Definitions:

Percentage

A rate, number, or amount in each hundred, represented by the symbol %.

Base

The fundamental component or main ingredient in a mixture, formula, or system.

Decimal Places

The number of digits to the right of the decimal point in a number, significant in precision of measurements and calculations.

Percent Increase

The ratio of the increase in value to the original value, expressed as a percentage.