Question

The cost of fencing a circular field at the rate of Rs 25 per metre is Rs 5500. The field is to be ploughed at the rate of 50 paise per m² . Find the cost of ploughing the field. [Take ${\displaystyle \pi =\frac{22}{7}}$].

Answer 1

Circumference${\displaystyle =\frac{\text{Total cost of fencing}}{\text{Rate of fencing}}=\frac{5500}{25}=220}$

Let the radius of the circle be r.

Now,

Circumference = 220

⇒ 2πr  = 220

⇒ r = 35 cm

Now,

Area of field=${\displaystyle \pi {\text{r}}^2=\frac{22}{7}\times {\left(35\right)}^2=3850 \text{cm}}$

Cost of ploughing = Rate ⨯ Area of field = 0.5 3850 = Rs 1925

Hence, the cost of ploughing the field is Rs 1925.