Confirm if this is correct or not. If it isn't correct, please correct it.

Answer:
d = 421.83 m
Explanation:
It is given that,
Height, h = 396.9 m
Horizontal speed, v = 46.87 m/s
We need to find the distance traveled by the ball horizontally. Let t is the time taken by the ball. Using second equation of motion for vertical direction. So,
[tex]396.9=0\times t+\dfrac{1}{2}\times 9.8 t^2\\\\t=9\ s[/tex]
Now d is the distance covered by the cannonball. So,
[tex]d=vt\\\\d=46.87\times 9\\\\d=421.83\ m[/tex]
Hence, this is the required solution.