A circular grassy plot of land, 42m in diameter, has a path 3.5m wide running round it on the outside. Find the cost of gravelling the path at Rs. 4 per square metre.

Explanation

Area of path= area of ring`=piR^2-pir^2`

`=pi(R-r)(R+r)`

`=22/7(24.5-21.0)(24.5+21)`

`=500.5m^2`

Cost of 1`m^2`=Rs4

cost of 500.5`m^2`=Rs 2002.