9514 1404 393
Answer:
4.12 seconds
Explanation:
Use the given initial height for Ball 2 to fill in that value in the function.
f(t) = -16t² +272
You want to find t when f(t) = 0.
0 = -16t² +272
0 = -t² +17 . . . . . . . divide by 16
t² = 17 . . . . . . . . . add t²
t = √17 ≈ 4.123 . . . . take the positive square root
Ball 2 reaches the ground after 4.12 seconds.