Question

An edge of a cube is increased by 10%. Find the percentage increase by which the surface area of cube has increased.

Answer 1

Let side of cube be a

Surface area = 6a^2
New side = a X 110/100 = 1.1a
New surface area = 6 X (1.1a)^2 = 6 X 1.21a^2 = 7.26a^2

Therefore, increase in area = 7.26a^2 - 6a^2 = 1.26a^2
Increase percentage = 1.26a^2/6a^2 X 100 = 21%