Question : If the length of a rectangular plot of land is increased by 5% and the breadth is decreased by 10%, how much will its area increase or decrease?
Option 1: 6.5% increase
Option 2: 5.5% decrease
Option 3: 5.5% increase
Option 4: 6.5% decrease
Correct Answer: 5.5% decrease
Solution :
Let $l$ be the length and $b$ be the breadth of the rectangle.
Area of a rectangle = Length $\times$ Breadth
Old area $=lb$
Length is increased by 5%.
$\therefore$ New length $=l+\frac{5}{100}l = 1.05l$
Also, Breadth is decreased by 10%.
$\therefore$ New breadth = $b-\frac{10}{100}b=0.9b$
$\therefore$ New area = $1.05l\times 0.9b = 0.945lb$
$\therefore$ Decrease in area = $\frac{\text{old area – new area}}{\text{old area}}\times 100$ = $\frac{lb-0.945lb}{lb}\times 100$ = 5.5%
Hence, the correct answer is a 5.5% decrease.
Related Questions
Know More about
Staff Selection Commission Sub Inspector ...
Result | Eligibility | Application | Selection Process | Cutoff | Admit Card | Preparation Tips
Get Updates Brochure
Your Staff Selection Commission Sub Inspector Exam brochure has been successfully mailed to your registered email id “”.
