Question

If the length of rectangle is increased by $20$% and breadth is decreased by $10$% then what will be the impact on area?

• A. $5$%
• B. $10$% increase
• C. $20$% decrease
• D. $8$% increase

Answer 1

The correct option is D $8$% increase

Let the length & breadth of rectangle be $a$ & $b$

Area(original)$=ab$

New length$=$ $a+\frac{20}{100}a$

$=\frac{120}{100}a$

New breadth$=b-\frac{10}{100}b$

$=\frac{90}{100}b$

Area(new)$=\frac{120}{100}\times \frac{90}{100}ab$

$=\frac{108}{100}ab$

$=ab+\frac{8}{100}ab$

$\therefore$ Area is increased by $8\%$.