1. Marcus is playing hang-glider catch while gliding along in a hang-glider. He and his friend, Aurelius, are tossing a ball back
and forth to each other as they fly 100 feet above the ground.
Aurelius is distracted by a passing pelican and drops the ball. The
height, h, in feet, of the ball above the ground is given by the
formula h(t) = -16t2 + 100, where t is the time in seconds.
To the nearest tenth of a second, after how many seconds does the
ball hit the ground?