Mensuration

The cost of fencing a circular field at the rate of ₹ 24 per meter is ₹ 5,280. The field is to be ploughed at the rate of ₹ 0.50 per square meter. Find the cost of ploughing the field.


Let radius of the circular field $=r$

Cost of fencing the circular field at the rate of ₹ 24 per meter = ₹ 5,280

$\implies$ Circumference of the circular field $= \dfrac{5280}{24} = 220 \ m$

i.e. $2 \pi r = 220$

$\implies$ $r = \dfrac{220}{2\pi} = \dfrac{110 \times 7}{22} = 35 \ m$

$\therefore$ Area of the circular field $= \pi r^2 = \dfrac{22}{7} \times 35^2 = 3850 \ m^2$

Cost of ploughing the field per square meter = ₹ 0.50

$\therefore$ Cost of ploughing the entire field $= 3850 \times 0.50 =$ ₹ 1,925