Posted by Anonymous on Wednesday, March 6, 2013 at 1:21pm.
In a survey randomly selected subjects, the mean age of the 36 respondents is 40.0 years and the standard deviation of the ages is 10.0 years. Use these sample results to construct a 95% confidence interval estimate of the mean age of the population from which the sample was selected.

statistics  Dr. Jane, Wednesday, March 6, 2013 at 1:24pm
95% confidence means that you will have 5% left in the two tails. Split this number in half to get .025 in each tail.
This is equivalent to a zscore of 1.96
Use this zscore in the formula to find the confidence interval.