tina2021-07-27 13:43:46

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 stocks 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 1.96. If he assumes that the S&P 500 return this year will be the same as it was last year, which of the following is the best estimate of the 95% confidence interval for this year's S&P 500 return? 老师你好，这道题为何是样本均值的估计呢？不应该是总体均值的估计呢？