Your friend says that the volume of a sphere with a radius r is four times the volume of a cone with radius r. when is this true? justify your answer

Volume of a sphere is given by the formula: 

If we pull the 4 out front we have, .

Volume of a cone is given by the formula: 

Notice that if the height of the cone is equal to the radius, 

then it's exactly what we see in our volume formula without the 4!