If a set of standardized test scores is normally distributed,having a mean of 75 and a standard deviation of 6,approximately 95 percent of the scores are somewhere between
A) 72 and 78.
B) 75 and 87.
C) 69 and 81.
D) 63 and 87.

Question

Quizplus · Accepted Answer

According to the empirical rule (68-95-99.7 rule) for a normal distribution, approximately 95% of the data falls within two standard deviations of the mean. Given a mean of 75 and a standard deviation of 6, two standard deviations from the mean would be from 75 - 2(6) = 63 to 75 + 2(6) = 87.

If a Set of Standardized Test Scores Is Normally Distributed,having