Given a normally distributed population wi

问题单项选择题

Given a normally distributed population with a mean income of $40000 and standard deviation of $ 7500, what percentage of the population makes between $ 30000 and $ 35000（）

A. 15.96.

B. 13.34.

C. 41.67.

答案

参考答案：A

解析：

The z - score for $ 30000 = ($ 30000-$ 40000)/$ 7500 or - 1.3333, which corresponds with 0.0918. The z - score for $ 35000 = ($ 35000-$ 40000)/$ 7500 or -0.6667, which corresponds with 0.2514. The difference is 0.1596 or 15.96%.