The volumes of the two spheres are in the ratio 64 : 27 and the sum of their radii is 7 cm. The difference of their total surface areas is

Question

Philoid · Accepted Answer

Volume of a sphere

Given Ratio of volumes of two spheres

So, r = 4x and R = 3x

Also given that the sum of radii = 7

⇒ r +R = 4x +3x =7x =7

⇒ x =1

So r = 4cm and R = 3cm

Surface area of a sphere

Difference in total surface area =