Question

edge of cube is increased by 50% then percentage of increase in surface area

Answer 1

let the side of cube be 'a' cm
so the original surface area is 6a^2.

increase % = 50%
so increased side = a + 50/100 x a
= a + a/2
= 3a/2
so the new surface area is 6(3a/2)^2
= 6(9a^2/4)
=27a^2/2
so percentage of increase in surface area = (27a^2/2 - 6a^2)/6a^2 x 100
= 15a^2/12a^2 x 100
= 125%

Answer 2

the new side becomes s+50%s=s+1/2s
=3/2s
so the new area is =6*(3/2s)(3/2s)
=(27/2)s2
difference=(27/2-6)s2
=7.5s2
% increase =(7.5/6)*100=125%