A smoke jumper jumps from a plane that is 1800 ft above the ground. The function h = - 16t2 + 1800 gives the jumper's height h in feet during the free fall at t seconds
a. How long is the jumper in free fall if the parachute opens at 1000 ft?
b. How long is the jumper in free fall if the parachute opens at 950 ft?
c. What is a reasonable domain and range for the function h?