Question 15 Marks
The length and the breadth of a rectangular field are in the ratio $7 : 4$. The cost of fencing the field at $Rs. 25$ per metre is $Rs. 3300.$ Find the dimensions of the field.
Answer
View full question & answer→Total cost of fencing a rectangular field $= Rs. 3300$
Rate of fencing $= Rs 25$ per m
$\therefore$ Perimeter $=\frac{\text{Total cost}}{\text{Rate}}$
$=\frac{3300}{25}$
$=132\text{m}$ And length + breadth $=\frac{\text{Perimeter}}{2}$
$=\frac{132}{2}$
$=66\text{m}$ Now ratio in length and breadth $= 7 : 4$
Let length $= 7x$
Then breadth $= 4x$
$\therefore 7x + 4x = 66$
$\Rightarrow 11x = 66$
$\therefore \text{x}=\frac{66}{11} = 6$
$\therefore$ Length of the field $= 7x = 7 \times 6 = 42m$ And
breadth $= 4x = 4 \times 6 = 24m$
Rate of fencing $= Rs 25$ per m
$\therefore$ Perimeter $=\frac{\text{Total cost}}{\text{Rate}}$
$=\frac{3300}{25}$
$=132\text{m}$ And length + breadth $=\frac{\text{Perimeter}}{2}$
$=\frac{132}{2}$
$=66\text{m}$ Now ratio in length and breadth $= 7 : 4$
Let length $= 7x$
Then breadth $= 4x$
$\therefore 7x + 4x = 66$
$\Rightarrow 11x = 66$
$\therefore \text{x}=\frac{66}{11} = 6$
$\therefore$ Length of the field $= 7x = 7 \times 6 = 42m$ And
breadth $= 4x = 4 \times 6 = 24m$



