题目

The figure above shows the standard normal distribution with mean 0 and standard deviation 1, including approximate percent of the distribution corresponding to the six regions shown above. The random variable x is normally distributed with standard deviation of 10 and value x = 135 is at the 20th percentile of the distribution. Of the following which is the best estimate of the mean of the distribution?


选项

A.

140

B.

150

C.

160

D.

165

E.

170

解析

如果考虑问题中给出的正态分布曲线, 我们知道第20百分位的值会位于“M – D”和“M”之间。 其中M为均值,D为标准差。 给定,20百分位处的值为135, 因此我们可以说“M – D”< x 135 135< M < 145。 在可选答案中,我们可以说 M = 140
在线客服
官方微信
公众号