The distribution of the annual incomes of a group of middle management employees approximated a normal distribution with a mean of $37,200 and a standard deviation of $800. About 68% of the incomes lie between what two incomes?
A)$30,000 and $40,000
B)$36,400 and $38,000
C)$34,800 and $39,600
D)$35,600 and $38,800

Question

Quizplus · Accepted Answer

According to the Empirical Rule, about 68% of data falls within one standard deviation of the mean. In this case, one standard deviation from the mean is $800. Therefore, approximately 68% of the data (middle 68%) falls between $37,200-$800 = $36,400 and $37,200+$800 = $38,000. So, the best choice is (B).

The Distribution of the Annual Incomes of a Group of Middle