问题如下图:
选项:
A.
B.
C.
解释:
讲义中正态分布一节的一道例题,题干如下:
A client holding a portfolio.The average return of the portfolio is 8% per year and the standard deviation of the portfolio is 12%.if return of the portfolio are approximately normal ,what is the 95% confidence interval for the portfolio return nect year?
答案解析是:8+-1.96*12%=-15.51%to
31.52%
请问为什么这道例题不用标准误的公式求解呢?什么时候应该用标准误呢