a) If you choose one student at random, what is the probability that he is between 69 and 71 inches tall?

b) What is the probability that the mean height of your sample is between 69 and 71 inches?

I'm trying to help someone taking this class now. When I learned it we used z-scores in order to find the percentile but they said they won't be allowed to use a chart on their test...and I have no clue how to solve this without using z-scores unless you use an integral which is beyond that class. Any help would be appreciated.