You want to obtain a sample to estimate a population mean age of the incoming fall term transfer students. Based on previous evidence, you believe the population standard deviation is approximately $\displaystyle \sigma={5.9}$. You would like to be 90% confident that your estimate is within 2.5 of the true population mean. How large of a sample size is required? 

n =

Do not round between steps. Use technology to find z-score. Give your answer in whole people. Make sure you use the correct rounding rule for samples size.