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.


(a) What percentage of students study between 7 and 9 hours per week?
(b) What is the amount of time below which 5% of all students spend studying? (round your answer to
2 decimal points)