Professor Kline has 125 students in his Western Civilization class. At the end of the semester, the average final grade was mean 68.85 and a standard deviation 7.25. Write down R code draw the standard normal curve, mark the shaded region for the following and find the how many students received a final score

(a). better than 90?

(b). between 70 and 85?

(c). less than 60.50?