Question:
The radius of a circular garden is 100 m. There is a road 10 m wide, running all around it. Find the area of the road and the cost of levelling
it at Rs 20 per m2. [Use π = 3.14]
Solution:
Area of the road = Area of outer circle − Area of inner circle
$=\pi R^{2}-\pi r^{2}$
$=\pi\left[(110)^{2}-(100)^{2}\right]$
$=3.14 \times 2100$
$=6594 \mathrm{~m}^{2}$
Cost of levelling the road = Area of the road ⨯ Rate
= 6594 ⨯ 20
= Rs 131880