Two cross roads each of width 3 m run at right angles through the centre of a rectangular park of length 100 m and breadth 80 m and parallel to its sides. Find the area of the roads. Also find the cost of constructing the roads at the rate of Rs. 11 per sq m.

Length (l) of park = 100 m

Breadth (b) of park = 80 m

Area of park = 100 × 80 = 8000 m2

Length of road PQRS = 100 m

Length of road ABCD = 80 m

Width of each road = 3 m

Area of the roads = ar (PQRS) + ar (ABCD) − ar (KLMN)

= (100 × 3) + (80 × 3) − (3 × 3)

= 300 + 240 − 9

 = 531 m2 

Cost of constructing 1 m2 of the road = Rs 11

Cost of constructing 531 m2 of the road = (531 × 11) = Rs 5841

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