问一道统计学问题：英文
问题描述：
问一道统计学问题：英文
Suppose a population has a mean of 90 and a standard deviation of 28.If a random sample of size 49 is drawn from the population,the probability of
drawing a sample with a mean of more than 95 is _________ .
Select one:
a.0.3944
b.1.0000
c.0.8944
d.0.4286
e.0.1056
我总觉得是a,但是不是应该X2的吗?为什么?
答
e
因为u=(95-90)/(28/√49)=1.25,查表得P=0.056 .