Answer:
t = 8.69 s
Step-by-step explanation:
The height h of the rocket in feet above the surface of the lake can be modeled by :
[tex]h=340+100t-16t^2[/tex]
Let we need to find the time to reach the ground. When it reach the ground, h = 0
[tex]340+100t-16t^2=0[/tex]
We need to find the value of t.
t = 8.69 s and -2.45 s
Neglecting negative value,
t = 8.69 s
Hence, it will take 8.69 s to reach the ground.