Subject: General Aptitude · Chapter: Area · Exam: 2008 · Marks: · Difficulty:
If each side of a rectangle is increased by 50\%, its area will increase by
(a)50\%
(b)125\%
(c)150\%
(d)200\%
Answer
Answer (as printed): B
Explanation
Let original length $=l$ metres and original breadth $=b$ metres. Original area $=(l b) \mathrm{m}^{2}$. New length $=\left(\frac{150}{100} l\right) \mathrm{m}=\left(\frac{3}{2} l\right) \mathrm{m}$; New breadth $=\left(\frac{150}{100} b\right) \mathrm{m}=\left(\frac{3}{2} b\right) \mathrm{m}$. New area $=\left(\frac{3}{2} l \times \frac{3}{2} b\right) \mathrm{m}^{2}=\left(\frac{9}{4} l b\right) \mathrm{m}^{2}$. ∴ Increase $\%=\left(\frac{5}{4} l b \times \frac{1}{l b} \times 100\right) \%=125 \%$.
Explanation as extracted from the printed page; notation may be imperfect.