We Would Like to Estimate the Average Amount of Time $\mathbf{9 0} \%$

Short Answer

We would like to estimate the average amount of time that all students at a certain college spent studying during Spring Weekend. We would like to be $\mathbf{9 0} \%$ confident that our estimate is within .5 hours of the actual population average.
-Find a $90 \%$ confidence interval for the average study time of all students at the college if the sample average was 3.5 hours.