What is the exact volume of a sphere that has a radius of 7.5ft

Since the equation for volume of a sphere is 4/3* π*r^3, you just plug in the radius. if you do this you get 4/3*421.875*π. multiply 4/3 and 421.875 and you get 562.5. now since it says EXACT, leave it in terms of pi; your answer would be 562.5π ft^3. if it said estimated or something along those lines then you would multiply by 3.14 but since it says exact you leave pi alone.