The distribution of scores on a test is mound-shaped and symmetric with a mean score of 78. If 68% of the scores fall between 72 and 84, which of the following is most likely to be the standard deviation of the distribution?
A) 6
B) 2
C) 12
D) 3

Question

Quizplus · Accepted Answer

The range from 72 to 84 represents one standard deviation from the mean in a normal distribution, which covers about 68% of the data. The difference between 78 and 72 (or 84) is 6, indicating the standard deviation is likely 6.

The Distribution of Scores on a Test Is Mound-Shaped and Symmetric