Let r be the radius of sphere 1. Then the radius of sphere 2 is 3r. The surface area of sphere 2 is
Since the surface area of sphere 1 is
the ratio SA1/SA2 would be
Now, you do the same thing with the volume. Remember that
sphere 1 has a surface area of A_1
and has a volume of V_1
sphere 2 has a surface area of A_2
and has a volume of V_2
if the radius of sphere 2 is 3 times greater than the radius of sphere 1,
what is the ratio A_1/A_2 of the surface areas?
what is the ration V_1/V_2 of the volumes?
_ means that the number is underscored like this -->A_1