Solution:
Given radius of the spherical balloon, r = 7 cm
Radius of the spherical balloon after air is pumped, R = 14 cm
Surface area of the sphere = 4r2
Ratio of surface areas of the balloons = 4r2/4R2
= r2/R2
= 72/142
= 1/4
Hence the ratio of the surface areas of the spheres is 1:4.