Question

If the edge of a cube is doubled then the ratio of total surface area of the new cube to the total surface area of the old cube is

(A) 2:1

(B) 4:1

(C) 6:1

(D) 8:1

Answer 1

Correct option is (B) 4:1

Let edge of cube be a.

\(\therefore\) Total surface are a of cube = 6a² = A₁

Edge of new cube = 2a

\(\therefore\) Total surface area of new cube = 6(2a)²

= 4(6a²)

= A₂ (Let)

\(\frac{A_2}{A_1} = \frac{4(6a^2)}{6a^2} = \frac41 = 4:1\)