Q16 of 37 Page 13

A circular park, 42m is a diameter, has a path 3.5 wide running round it on the outside. Find the cost of gravelling the path at Rs. 4 per m2


The diameter of a circular park = 42m


⇒ the radius of a circular park,


Width of path = 3.5m


⇒ radius of the park with path, R = 21 + 3.5 = 24.5m


∴ Area of path = Area of outer circle – Area of the inner circle


= πR2 – πr2


= π (R2 – r2)


= π (R – r)(R + r)




= 22 × 0.5 × 45.5


= 500.5 m2


Now, the cost of gravelling the path of 1m2 = Rs 4


the cost of gravelling the path of 500.5m2 = Rs 4×500.5


= Rs 2002


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