单选题

An analyst wants to estimate the return on the S&P 500 Index for the current year using the following data and assumptions:
Sample size = 50 securities from the index
·Mean return for those stocks in the sample for the previous year = 0.114
·Variance = 0.0529
·The reliability factor for a 95% confidence interval with unknown population variance and sample size greater than 30 is

A、 –0.11600 to +0.34400
B、 +0.05024 to +0.17775
C、 +0.06110 to +0.16690

【正确答案】 B

【答案解析】

B is correct. The reliability factor for a 95% confidence interval with unknown population variance and sample size greater than 30 is Z_0.025=1.96.
The confidence interval estimate is
With sample variance of 0.0529,The estimated interval is|