Question

In ploughing a filed, at the rate of $50$ paise per square metre, the total expenditure is Rs. $5400$. If the sides of the field are in the ratio of $4:3$, calculate the time taken by a boy(in second) running at the rate of $10$ metres per second, in completing a round.

Answer 1

Area of the filed $=\frac{\text{Total cost}}{\text{Cost per unit area}}$
$=\frac{5400}{50}=10800$ sq.m.
Let the sides be 4x and 3x.
$\therefore 4x\times 3x=10800$
$x^2=900$
$x=30$
Hence, sides are $120$ metre and $90$ metres.
$\therefore$ Perimeter $=2(120+90)$
$=420$ metres.
$\therefore Time=\frac{\text{Distance (Perimeter )}}{Speed}=\frac{420}{10}=42seconds.$