Question

The length of a rectangular field is thrice its breadth and its perimeter is 240 m. The length of the field is

(a) 80 m
(b) 120 m
(c) 90 m
(d) none of these

Answer 1

(c) 90 m

Let the breadth of the rectangular field be x m.
Length = 3x m
Perimeter of the rectangular field = 2(l + b)
⇒ 240 = 2( x + 3x)
⇒ 240 = 2(4x)
⇒ 240 = 8x ⇒ x = $\left(\frac{240}{8}\right)=30$
∴ Length of the field = 3x = (3 × 30) m = 90 m