Mathematics for IGCSE & O level - Proportion (Section 1 - No. 19)
If the volume (V) of a sphere is proportional to the cube of its radius (r), which of these equations is correct?
V = kr
V = kr^2
V = kr^3
V = k/r
Explication
The volume of a sphere is proportional to the cube of the radius means V = kr^3.