Question

The radius of spherical balloon increases from 7 cm to 14 cm if air is pumped into it find the ratio of surface area of balloon in two cases

Answer 1

first case:

radius= 7cm

$surface \: area \: of \: sphere = 4\pi \: r ^{2}$

= 4 x 22/7 x (7)^2

= 616 cm^2

second case:

radius = 14cm

surface area= 4 x 22/7 x(14)^2

= 2464 cm^2

ratio of both surface areas = 2464/616

= 1/4

= 1:4