Answer:
t = 8.69 s
Explanation:
The height h of the rocket in feet above the surface of the lake can be modeled by :
![h=340+100t-16t^2](https://img.qammunity.org/2021/formulas/mathematics/high-school/d27lfsk82v07rpiyn6a8padldpb0lfbw2r.png)
Let we need to find the time to reach the ground. When it reach the ground, h = 0
![340+100t-16t^2=0](https://img.qammunity.org/2021/formulas/mathematics/high-school/93jxvsnx2s396bg06bffad7musu8hoos3t.png)
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.