Assume that the population is normal. A sample of size 100 is taken. The resultant sample data has a mean of 48 and a standard deviation of 15. Construct the 99% confidence interval for the population mean.
This mean .005 at each tail. Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion (.005) and its Z score.
99% = mean ± 2.575 SEm
SEm = SD/√n