The percentage increase in the surface area of a cube when each side is doubled is :

Answer: Option B

We know that
⇒ Total surface area of a cube
⇒ 6a²
⇒ If each side is doubled i.e. 2a
⇒ Total surface area of a cube
⇒ 6 × (2a)²
⇒ 24a²
Increase in surface area = 24a² - 6a² = 18a²
∴ % Surface area of cube will increase :
$$\frac{18a^2}{6a^2}\times 100$$
= 300%