NO.PZ2015120604000178
问题如下:
BIM is a well-developed public company and its market capitalization growth rates over past few decades are normally distributed.The population has a mean of 10% and a standard deviation of 5.4%. An investor wants to figure out the probability that BIM's average capitalization growth rate will over 12.32% in the next three years (all the data are monthly statistics).Which of the following option is most accurate?
选项:
A.
0.5%.
B.
1%.
C.
5%.
解释:
A is correct.
It is appropriate to use the central limit theroy to calculate.Standard error=5.4%/P(X>12.32%)=P(Z> (12.32%-10%)/0.009)=P(Z>2.58). So the corresponding probability is 0.5%.
① 为什么不是除以方差5.4%;而是除以标准误。 我看了有些人提问,老师的回答提到了总体和样本 的关系不能直接除。但是我还是不理解! ②这个题,如果不是出在这个练习题章节,而是整体的一个考试。我们怎么判断说,原来正态分布中标准化的分母,不能用题干的分母,而是要用一个标准误做分母呢?