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)2
B)12
C)3
D)6

Question

Quizplus · Accepted Answer

In a normal distribution, approximately 68% of the data falls within one standard deviation of the mean. Since the scores between 72 and 84 represent this range, the standard deviation is likely 6, as 78 ± 6 gives the range 72 to 84.

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