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
11-u/standard deviation =-1.96 35–u/sd =1.96