If every side of a cube is increased by 25%, then what will be percentage increase in the surface area - 

56.25 %

Side of a cube = a

Surface area (S.A.) of cube = 6a²

25% = \(\frac{1}{4}\)

ATQ,

           Actual   :   New

side ⇒     4      :     5                 (a : b)

S.A. ⇒    6a²     :   6b²

       ⇒     a²     :     b²

       ⇒     4²     :     5²

       ⇒     16     :    25

Increased in surface area = 25 - 16 = 9

Increased percentage = \(\frac{9}{16}\) × 100 = 56.25%