Suppose the sphere below with radius r has a volume equal to 30 units3 Find the volume of the sphere with twice the radius?

4/3*pi*r3 = 30 cubic units

Make r the subject of the formula in order to find the radius:

radius = 1.92757321 units

2*radius =3.85514642

Volume = 4/3*pi*3.855146423 = 239.9999998 or 240 cubic units