Given: The side of a cube is increased by 50% Concept used: The total surface area of a cube with side 'a' = 6 × a2 Calculation: The total surface area of a cube with side 'a', = 6a2 ⇒ S = 6 × a2 New length of the side = a × 150% = 3a/2 The total surface area of the new cube with side '3a/2', ⇒ SN = 6 × (3
a
2
)2 ⇒ SN = 6 × a2×(
3
2
)2 ⇒ SN = S × 9/4 ⇒
SN
S
= 9/4 Increase in total surface area =
(SN−S)
S
× 100 ⇒ (9 - 4)/4 × 100 ⇒ 125% ∴ The total surface area increased by 125%.