The main assumption here is that the height at the water level is 0.
So, the answer is given by the solution to the equation
- 16t^2 + 16t + 480 = 0
To solve it, start dividing by -16 to get:
t^2 - t - 30 = 0.
Now factor the left side:
(t - ) (t + ) =0
Find two numbers that add - 1 and its product is -30
(t - 6 ) (t + 5 ) =0
That gives:
t - 6 = 0 ⇒ t = 6 seconds
The other result gives a time negative, which makes not sense for the problem.
Verify substituing 6 in the original equation:
h(6) = -16*6^2 + 16*6 + 480 = -576 + 96 + 480 = 0. Lo cual confirma nuestra solucion.
It toke Rose 6 seconds to hit the water.
