Final answer:
The rock takes about 4 seconds to reach the water.
Step-by-step explanation:
The function h(t) = -16t² + 48t + 64 represents the height of the rock in feet t seconds after it was thrown. In this equation, t represents time and h(t) represents the height of the rock.
To find the time it takes for the rock to reach the water, we need to find when the height is equal to zero. Set h(t) = 0 and solve for t:
-16t² + 48t + 64 = 0
By factoring or using the quadratic formula, you can solve for t and find that the rock takes about 4 seconds to reach the water.
Learn more about Time taken for a rock to hit water