NO.PZ2019040801000025
问题如下:
Assuming the height of a tree in a forest follows a normal distribution, there are more than 10,000 trees. The sample size of test is 200, the 95% confidence interval of the sample mean of the height is 11 to 35 meters based on a z-statistic, the standard error of mean height is closest to:
选项:
A.
1.96.
B.
3.58.
C.
6.12.
D.
10.50.
解释:
C is correct.
考点:The central limit theorem (CLT)
解析:95%的置信区间是11到 35,z值是1.96.
平均数为0.5*(11+35)=23.所以置信区间是23 ± 1.96sx, sx是标准误。23+1.96sx等于35,sx等于6.12米
老师,这个样本(容量200)的均值为什么是(11+35)/2呢?如果这么算不就相当样本容量2棵树,一颗高度11,一颗高度35?