Question

the radius of a spherical ball on increase from 7cm to 14cm as air pumped into it find the ration of the balloon before and after pumping the air​

Answer 1

R = radius of ballon = 7cm

r = radius of pumped ballon = 14cm

$\frac{surface area of balloon before inflating}{surface area of balloon after inflating}$

=4×(22/7)×R×R / 4 × (22/7) × r×r

= R×R/r×r

=7×7/14×14

= 49 / 196

= 1:4