The formula of the volume of a cylinder:
[tex]V=\pi r^2H[/tex]
r - a radius of a base
H - a height of a cylinder
We have:
[tex]V=63,679\ ft^3\\H=30\ ft[/tex]
Substitute:
[tex]\pi r^2\cdot30=63,679\ \ \ |:30\pi\\\\r^2=\dfrac{63,679}{30\pi}\to r=\sqrt{\dfrac{63,679\pi}{30}}\ ft\\\\r\approx81.66\ ft[/tex]
