Question

The volume of a cube is numerically equal to sum of its edges. What is the total surface area in square units ?

(a) 12 

(b) 36 

(c) 72 

(d) 144

Answer 1

(c) 72

Let a be the length of an edge of a cube. Then, 

a³ = 12a            (∵ A cube has 12 edges) 

⇒ a² = 12 ⇒ a = 2√3 

∴ Total surface area of cube = 6a² = 6 x (2√3)² = 72.