Answer:
t = 1.5; it takes 1.5 seconds to reach the maximum height and 1.5 seconds to fall back to the ground
Explanation:
The axis of symmetry of a parabola is halfway between the zeros.
h(t) = -16t² + 48t
0 = -16t² + 48t
0 = -16t (t − 3)
t = 0, t = 3
The zeros are t = 0 and t = 3, so the axis of symmetry is t = 1.5. That means it takes 1.5 seconds to reach the maximum height and another 1.5 seconds to return to the ground.