You can
put this solution on YOUR website!The formula for the volume of a sphere is
(1)

Making the sphere seven times smaller means
multiplying

by

Let

= the new radius when

is

of what it used to be
(2)

Now I need to find

in terms of

Multiply both sides of (1) by

(2)

(2)

Now I need to substitute

in (1) for

in (2)
(2)

(2)

Now take the cube root of both sides
(2)

is the reduced radius in terms of

The surface areas are proportional to

and

Because

so I can rewrite (2) as
(2)

(2)

Now square both sides

This is the factor that the surface area changes by