题目
The mean age of the 80 employees in a company is 35 and the standard deviation is 15. Assuming that the ages are normally distributed and using 95% confidence level, we can say that the employees within the firm fall between:
选项
A.20.0 and 50.0 years
B.31.7 and 38.3 years
C.33.8 and 36.2 years
D.34.6 and 35.4 years
答案
B
解析
Therange of the 95% confidence interval=μ±1.96×σ/√n=35±1.96×15/√80=(31.7298 ,38.2702) 95％置信区间的范围=±1.96×σ/√n=35±1.96×15/√80=(31.7298,38.2702)