A ball is thrown vertically upward from the ground. Its distance in feet from the ground in t seconds is s=-16t^2+208t. After how many seconds will the ball be 640 feet from the ground?

Answer 1

solve -16t^2+208t = 640
t^2 - 13t + 40 = 0
(t-5)(t-8) = 0

t = .....

interpret this result

Answer 2

Quite a throw.

Answer 3

And that wasn't even the maximum height !!!