Question

The radius of a spherical balloon increases from 7 cm to 14 cm as air is being pumped into it. Find the ratio of surface areas of a balloon in the two cases

Answer 1

(4/3π rcube)/(4/3π r'cube) = r cube/r'cube

=7cube/14cube

=7×7×7/14×14×14

=1×1×1/2×2×2

=1/8

=1:8