SSC CHSL 4 Mar 2018 Shift 1 Paper

Let both length and breadth of the rectangle be $\mathit{l}=10$ cm and $\mathit{b}=10$ cm
Area of rectangle = $\mathit{A}=\mathit{l}\times \mathit{b}=10\times 10=100\mathit{c}{\mathit{m}}^2$
New length when it is increased by 10% = $\mathit{l}\prime =10+\left(\frac{10}{100}\times 10\right)=11$ cm
Similarly, new breadth when it is increased by 20% = $\mathit{b}\prime =10+\left(\frac{20}{100}\times 10\right)=12\mathit{c}\mathit{m}$
⇒ New area = $\mathit{A}\prime =11\times 12=132\mathit{c}{\mathit{m}}^2$
∴ % increase = $\frac{\left(132-100\right)}{100}\times 100=32\%$