The amount of time devoted to studying statistics each week by students who achieve a grade of A in the course is a normally distributed random variable, with a mean of 7.5 hours and a standard...

The amount of time devoted to studying statistics each week by students who achieve a grade of A in the course is a normally distributed random variable, with a mean of 7.5 hours and a standard deviation of 2.1 hours. Also indicate whether the event is usual or unusual

A.  What proportion of A students study more than 10 hours per week

B.  Find the probability that an A student spends between 7 and 9 hours studying

C.  What proportion of A students spend fewer than 3 hours studying

*Please do not solve using Microsoft Excel.  My professor is not teaching using excel.  I would like to see the steps involved to solving the problem for my own study reference for exams.*