Question: Suppose the monthly percentage changes in the TSE 300 index from 1980 to 2000 are normally distributed with a standard deviation of 2.05 percentage points. We wish to estimate the mean value of monthly percentage changes during this period. To do so, we randomly selected a sample of 20 such changes, the values of which are as follows:
3.92 1.69 1.79 -1.00 -2.05 1.41 2.65 -1.09 3.92 1.48
2.00 0.85 0.31 1.46 3.92 .094 0.46 2.91 0.23 0.71
Find a 90 percent confidence interval estimate of the population mean.
Find a 95 percent confidence interval estimate of the population mean.