A park is of the shape of a circle of diameter 7 m. It is surrounded by a path of width 0.7 m. Find the expenditure of cementing the path, if its cost is Rs 110 per sq. m.

Explanation

Radius of circular park `r = 3.5 m`
There is a path of width 0.7m
So, radius of external circle `R = 3.5 + 0.7`
`rArr R = 4.2 cm`
Area of path `= pi R^(2) - pi r^(2) = pi (R - r) (R + r)`
`= (22)/(7) (4.2 - 3.5) (4.2 + 3.5)`
`= (22)/(7) xx 0.7 xx 7.7 = 16.94 m^(2)`
Now, cost of cementing `1m^(2)` of path = Rs 110
`:.` Cost of cementing `16.94 m^(2)` of path `= Rs (110 xx 16.94) = Rs 1863.40`