Remember, the volume formula of a sphere is

.
Set that equation equal to whatever volume they give you and solve for r.

=

Now solve for r! I know you can do this. If you need help, just comment.
A triangle with sides measuring 300, 400 and 700 because 300+400+700=1400 which is higher than the first triangle 300+400+500=1200
Uhhhhh the picture is all white