Apply the 68-95-99.7 Rule to Answer the Question

question 45

Multiple Choice

Apply the 68-95-99.7 rule to answer the question.
-The lifetimes of light bulbs of a particular type are normally distributed with a mean of 310 hours and a standard deviation of 9 hours. What percentage of the bulbs have lifetimes that lie within 2 standard deviations to either side of the mean?

• A)98%
• B)68%
• C)95%
• D)99.7%

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Definitions:

Sampling Error

The difference between the characteristics of a sample and those of the population from which it was drawn, arising purely by chance.

Directional Research Hypothesis

A hypothesis that specifies the direction of the expected difference or relationship between variables, predicting how one variable will affect another.

Nondirectional Research Hypothesis

A hypothesis that predicts a relationship between variables without specifying the direction of the relationship.