If the area of a square increase by 69%, then the side of the square increases by :

Answer: Option B

Le original area = 100 cm²
Then, new area = 169 cm²
⇒ Original side = 10 cm
New side = 13 cm
Increase on 10 cm = 3 cm
Increase % :
$$\begin{array}{rl}& =\left(\frac{3}{10}\times 100\right)\%\\ & =30\%\end{array}$$