单选题 An analyst does research about confidence interval and gathers the following information about a stock return. The mean return of the stock is 11.5%. The standard deviation of returns of the stock is 1.8%. The lower endpoint of a confidence interval for the population mean with a reliability factor of 1.5 is closest to:
A. 8.8%
B. 9.7%
C. 14.2%

【正确答案】 A

【答案解析】[解析] 置信区间的下限=11.5%-1.5×1.8%=8.8%。