A population of scores is normally distributed with a mean of 100 and a standard deviation of 20. Approximately percent of the scores fall in the interval between 80 and 100.
A)14
B)34
C)68
D)84

Question

Quizplus · Accepted Answer

We can use the empirical rule for a normal distribution to estimate the percentage of scores that fall within 1 standard deviation of the mean. This rule states that approximately 68% of scores fall within one standard deviation of the mean. Since the mean is 100 and the standard deviation is 20, one standard deviation below the mean is 80. Therefore, approximately 34% of scores fall between 80 and 100.

A Population of Scores Is Normally Distributed with a Mean