A sphere is inside a cube.The diameter of the sphere is equal to the edge length of the cube. What portion of the volume of the cube is taken up by the sphere?

If the radius of the sphere is r then the length of a side of the cube is 2r.

Volume of the cube: (2r)^{3} = 8r^{3}.

Volume of the sphere: (4/3)·pi·r^{3}.

Portion: (4/3)·pi·r^{3} / (8r^{3}) = pi/6