The volume of a sphere is 288π ft3. What is the radius of the sphere?

So we have

288π ft³ = (4/3)πr³     divide both sides by π

288ft³ = (4/3)r³    multiply both sides by (3/4)

(3/4)288ft³ = r³    

216ft³ = r³       take the cube root of both sides

r = 6 ft.