Use the empirical rule to solve the problem.
-The lifetimes of lightbulbs of a particular type are normally distributed with a mean of 400 hours and a standard deviation of 12 hours. What percentage of the bulbs have lifetimes that lie within 2 Standard deviations to either side of the mean?
A)97.72%
B)99.74%
C)95.44%
D)68.26%

Question

Use the empirical rule to solve the problem.
-The lifetimes of lightbulbs of a particular type are normally distributed with a mean of 400 hours and a standard deviation of 12 hours. What percentage of the bulbs have lifetimes that lie within 2 Standard deviations to either side of the mean? 
A)97.72%
B)99.74%
C)95.44%
D)68.26%

Quizplus · Accepted Answer

The empirical rule states that for a normal distribution, approximately 95% of the data falls within 2 standard deviations of the mean.

Use the Empirical Rule to Solve the Problem