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Question
The sides of a rectangular park are in the ratio 4 : 3. If its area is 1728 m2, find
(i) its perimeter
(ii) cost of fencing it at the rate of ₹40 per meter.
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Solution
Ratio in the sides of a rectangle = 4 : 3
Area = 1728 m2
Let length = 4x, and breadth = 3x
∴ Area = l × b
1728 = 4x × 3x
⇒ 12x2 = 1728
⇒ `"x"^2=1728/12`
⇒ x2 = 144 = (12)2
∴ x = 12
∴ Length = 4x = 4 × 12 = 48 m
Breadth = 3x = 3 × 12 = 36 m
(i) Now perimeter = 2(l + b)
= 2(48 + 36) m
= 2 × 84 = 168 m
(ii) Rate of fencing = ₹40 per metre
Total cost = 168 × 40 = ₹6720
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