statistics
posted by martha .
The following list is a sampling of the costs of various statistics textbooks used at several colleges. Give the upper confidence limit for a 95% confidence interval estimate for the mean cost of all statistics textbooks.
109.95; 92.00; 96.70; 84.85; 92.60; 84.45; 90.95; 77.00; 75.50

Formula:
CI95 = mean ± 1.96(sd/√n)
You will need to calculate the mean and standard deviation for your data. In the formula, n = sample size.
Once you have what you need, substitute into the formula and determine the confidence interval.
I hope this will help get you started. 
28.22