Posted by Jelian on .
The U.S. Dairy Industry wants to estimate the mean yearly milk consumption. A sample of 20 people reveals the mean yearly consumption to be 72 gallons with a standard deviation of 15 gallons. What is the 99% confidence interval for the population mean?

statistics 
PsyDAG,
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion of .005 to get Z value.
99% = mean ± 2.575 SD