单选题 The 95 % confidence interval for the population mean based on a sample of 40 interest rates with a sample mean of 4% and a sample standard deviation of 15% is closest to:

A、

A. -0.851% to 8.851%.
B、

B. 1.261% to 6.739%.
C、

C. -0.794% to 8.794%.

【正确答案】 C

【答案解析】The standard error for the mean =