Question

if edge of a cube is increased by 25% find the increase it surface area.

Answer 1

original surface area=6s^2 where s is the side
new side=25%s+s=5/4s
new surface area = 6(5/4s)^2=150/16s^2
increase in surface area=84/16s^2
% increase=increased/original x100
=87.5%

Answer 2

let us suppose initial side of cube is "a"
after increasing it by 25% it will become "1.25a"
total surface area of cube is 6a2
hence now it become 6(1.25a)2
so ℅ increase in surface area is 6(1.25a)2 - 6 (a)2/6(a)2 * 100 = 56.25℅