Answer:
6 seconds after it is launched
Explanation:
h(t) = -4t² + 16t + 48
The balloon is at ground level when it lands.
When it is launched, t = 0, and h(0) = 48
When it lands, at time t, h(t) = 0.
-4t² + 16t + 48 = 0
t² - 4t - 12 = 0
(t - 6)(t + 2) = 0
t = 6 or t = -2
The balloon will hit the ground 6 seconds after it is launched.