Question

The diameter of a circular park is 42m. A 3.5m wide path runs around it from inside. Find the path at Rs. 2 per sqm

Answer 1

Hey Priyanka! I hope you know how the diagram for this question will be.

The outer radius of path R= 42/2= 21m
width of path = 3.5m
the inner radius of path r=21-3.5=17.5m

Area of path = area of outer circle - area of inner circle
                   = πR² - πr²
                   = π×21² - π×17.5²
                   =423.115 m²
Price @rs.2 per m² = 423.115*2 = Rs. 846.23

Answer 2

We need to find the area of the circular path.  This is equal to the difference between the areas of circle of radius 42/2 = 21 m  and  21 - 3.5m = 17.5 m.

Area of circular path = π (21²  - 17.5²) = π * 7² * 2.75  m²  = 423.33 m²

Cost of laying the road = area * rate = Rs  269.5 π  = Rs  846.66