Question

Expenses of painting a wall from one side at the rate of $35$ per square metre are Rs. $21000$. If the breadth of the wall is two-third of its length, what is the perimeter?

• A. $140m$
• B. $100m$
• C. $240m$
• D. $120m$

Answer 1

Answer: (B)

$100m$

Area of wall $=\frac{\text{Total expenses}}{\text{Rate}}=\frac{21000}{35}$
$=600$ sq m

Now $B=\frac{2}{3}L$ and $L\times B=600m^2$

$\Rightarrow L\times \frac{2}{3}L=600L^2=\frac{600\times 3}{2}=900m^2$
$\Rightarrow L=30m\Rightarrow B=20m$

$\Rightarrow Perimeter=2(L+B)$

$\Rightarrow Perimeter=2(30+20)m=100m$