题目
Based on a sample size of 100 and sample mean of $30, you estimate a 95% confidence interval for the mean weekly soft drink expenditures of students at a local college. Your estimate of the confidence interval is $26.77 to $33.23. Since you knew the standard deviation beforehand, your confidence interval was based on a standard deviation closest to:
选项
A.1.65
B.6.59
C.11.53
D.16.48
答案
D
解析
With a sample size of 100, we can use normal distribution as an approximation. Thus, the 95% confidence interval is「huixue_img/importSubject/1564169387626336256.png」.Given the confidence interval, we can solve the problem.σ=3.23×10/1.96=16.4796