Question

The cost of fencing a circular field at the rate of Rs.250 per metre is Rs.55000. The field is to be ploughing at the rate of Rs.15 per m². Find the cost of ploughing the field.

Answer 1

Let the radius of the circular field = r m
⇒ Circumference of the field = 2πr m
Now, the cost of fencing the circular field at Rs.250/m = Rs.55000
⇒ 2πr x 250 = 55000

⇒ `2 xx (22)/(7) xx "r" xx 250` = 55000

⇒ r = `(55000 xx 7)/(2 xx 22 xx 250)`
= 35m
Now, the area of the field
= πr²

= `(22)/(7) xx 35 xx 35`
= 3850m²
Thus, the cost of ploughing the field at the rate of Rs.15/m²
= Rs.15 x 3850
= Rs.57750.