NO.PZ2015120604000125
问题如下:
The population is 6000 programmer which is supposed to be normally distributed. A sample with 100 size is drawn from the population. Based on z-statistic, 95% confidence interval of sample mean of annual salary is 32.5 (in thousands) dollars ranges from 22 (in thousands) dollars to 43 (in thousands) dollars .Calculate the standard error of mean annual salary:
选项:
A.1.96.
B.3.99.
C.5.36.
解释:
C is correct.
At the 95% level of significance, the critical value is .
So the confidence interval is ,
From the equation t 32.5 + 1.96 σ = 43 or 32.5 - 1.96σ = 22, we get
我不知道是我哪里的知识缺了一块吗。为什么根据z表,95%的置信区间求出来的critical value 是1.96.。。。不应该是1.65吗。。。。。