The area of the circular garden is equal to the area of rectangle with length of 140 m and width of 110 m. Outside the garden, a road of 7 m width laid around the circular garden. If the cost of laying road is Rs. 5 per m2 then, what would be the cost of laying road (in Rs.)?
The area of the circular garden is equal to the area of rectangle with length of 140 m and width of 110 m. Outside the garden, a road of 7 m width laid around the circular garden. If the cost of laying road is Rs. 5 per m2 then, what would be the cost of laying road (in Rs.)? Correct Answer 16,170
Given:
Area of circular garden = Area of rectangle
Length of rectangle = 140 m
Breadth of rectangle = 110 m
Road width = 7 m
Rate of laying road = Rs. 5 per m2
Formula Used:
Area of rectangle = (length × breadth)
Area of circular garden = πr2
Calculation:
Area of rectangle = (140 × 110) = 15400 sq. m
Area of circular garden = πr2
⇒ 22/7 × r2 = 15400
⇒ r2 = 4900
⇒ r = √(4900)
⇒ r = 70 m
∴ OA = 70 m, OB = 77 m
Area of road = π(OB2 – OA2)
⇒ 22/7 × (772 – 702)
⇒ 22/7 × (5929 – 4900)
⇒ 22/7 × 1029
⇒ 22 × 147
⇒ 3234 sq. m
∴ Total cost of laying road = Rs. (3234 × 5)
⇒ Rs. 16,170