A distribution is approximately normal with a population mean of 80 and population standard deviation of 9. Approximately what percentage of scores fall between 71 and 89?
A) About 1/3
B) About 2/3
C) About 95%
D) About 99%

Question

Quizplus · Accepted Answer

Using the empirical rule for normal distributions, approximately 68% (or about 2/3) of the data falls within one standard deviation (σ) of the mean (μ). Here, one standard deviation from the mean ranges from 71 (80 - 9) to 89 (80 + 9).

A Distribution Is Approximately Normal with a Population Mean of 80