Use the 68-95-99.7 rule to solve the problem.
-The amount of Jen's monthly phone bill is normally distributed with a mean of $70 and a standard deviation of $9. What percentage of her phone bills are between $43 and $97?
A)68%
B)95%
C)99.9%
D)99.7%

Question

Quizplus · Accepted Answer

The 68-95-99.7 rule, also known as the empirical 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. The range from $43 to $97 is $27 below and above the mean ($70), which is exactly three standard deviations ($9 * 3 = $27). Therefore, approximately 99.7% of Jen's phone bills are between $43 and $97.

Use the 68-95-99.7 Rule to Solve the Problem