Use the empirical rule to solve the problem.
-The amount of Jen's monthly phone bill is normally distributed with a mean of $78 and a standard deviation of $9. What percentage of her phone bills are between $51 and $105?
A)68%
B)95%
C)99.7%
D)99.99%

Question

Quizplus · Accepted Answer

The empirical rule, also known as the 68-95-99.7 rule, states that for a normal distribution, approximately 68% of the data falls within one standard deviation of the mean, 95% falls within two standard deviations, and 99.7% falls within three standard deviations. In this case, $51 to $105 is three standard deviations away from the mean ($78 ± 3*$9), so 99.7% of her phone bills fall within this range.

Use the Empirical Rule to Solve the Problem