The volume of a sphere is given by the equation:
[tex]V=\frac{4}{3}\pi r^3[/tex]In this case, we have the diameter of the sphere, to find the radius (r), we just have to divide the diameter by 2:
[tex]r=\frac{D}{2}=\frac{12}{2}=6[/tex]Now, we just have to replace the value of r into the equation of the volume, like this:
[tex]V=\frac{4}{3}\pi(6)^3\approx904.8[/tex]Then, the volume of this sphere is 904.8 ft^3