If the diameter of the sphere is increased by 20%. By what % does its curved surface area increase?

Curved surface area of sphere = 2πr * 2r=4πr^2;

The new diameter is 120/100 from the old diameter;

2R = (120/100) x (2r);

So, R = 1.2 x r;

Curved surface area of new sphere = 4πR^2 = 4π (1.2xr) ^2 = 4πr^2x1.44 = curved surface of old sphere x (144%);

Finnaly, the increase is 44%.