Question

If each edge of a cube is increased by 50% then the percentage increase in the surface area is

• A. 50
• B. 125
• C. 150
• D. 300

Answer 1

The correct option is B 125

Let the edge of cube is x

Then surface area of cube =$6x^2$

After increased 50% edge =$\frac{150}{100}x=\frac{3x}{2}$

Then new surface area =$6\times \frac{3x}{2}=\frac{27x^2}{2}$

Then increased surface=$\frac{27x^2}{2}-6x^2=\frac{27x^2-12x^2}{2}=\frac{15x^2}{2}$

So % increased of surface area=$\frac{\frac{15x^2}{2}}{6x^2}\times 100=\frac{15x^2}{12x^2}\times 100=125$ %