Question 71

If each edge of a cube is increased by 10% then by how much percent will the surface area of this cube be increased ?

Solution

Let edge of cube, $$a = 10$$ cm

Surface Area, $$S = 6 a^2 = 6 (10)^2 = 600 cm^2$$

When edge is increased by 10%

=> New edge of cube, $$a' = 10 + \frac{10}{100} \times 10 = 11$$ cm

New surface area, $$S' = 6 (a')^2 = 6 (11)^2 = 726 cm^2$$

$$\therefore$$ % increase in surface area = $$\frac{726 - 600}{600} \times 100$$

= $$\frac{126}{6} = 21 \%$$

Create a FREE account and get: