Please answer and explain A-C so I can grasp the concept.

A new roller coaster at an amusement park requires individuals to be at least 4' 8" (56 inches) tail to ride. It is estimated that the heights of 10-year-old boys are normally distributed with p = 53.5 inches and a = 4 inches. a. What proportion of 10-year-old boys is tall enough to ride the coaster? b. A smaller coaster has a height requirement of 50 inches to ride. What proportion of 10-year-old boys is tall enough to ride this coaster? c. What proportion of 10-year-old boys is tall enough to ride the coaster in part b but not tall enough to ride the coaster in part a? a. The proportion of 10-year-old boys tall enough to ride the coaster is (Round to four decimal places as needed.)