How do I find the volume of a sphere?

The equation for the volume of a sphere is:v = 4/3 x pi x r^3
from this we can see the information we need to find out is the radius of sphere.
in this example the radius is 2cm. therefore, the volume is:
v = 4/3 x pi x 2^3 = 4/3 x 8 x pi = 32/3 pi = 33.5cm^3 to 3.s.f