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.

Answer 1

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