Thomas Edison, CFA, is an investment consu

问题单项选择题

Thomas Edison, CFA, is an investment consultant in the London office of Dalton Securities and forecasts next year's performance of securities market. According to Chebyshev's inequality, the minimum proportion of observations falling within ±3 standard deviations of the mean is closest to:（）

A. 50%

B. 89%

C. 94%

答案

参考答案：B

解析：

切比雪夫不等式(Chebyshev's inequality)说明，对于任何观察数集，无论样本或总体数据，也不管分布的形状如何，落在均值附近K个标准差范围内的观察值的比例至少为1-1/K²(只要K＞1)。根据公式，题目中K=3，可以得出1-1/K²=89%。