Question

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

(a) 30 m (b) 120 m (c) 90 m (d) 80 m

Answer 1

Let l and b be the length and breadth of the rectangular field, then l = 3b.
So, as per the question
Perimeter = 2 (l + b)
$$\begin{gathered} \Rightarrow 240=2\left(3b+b\right) \\ \Rightarrow 8b=240 \\ \Rightarrow b=30\mathrm{m} \end{gathered}$$
$l=3b=3\times 30=90\mathrm{m}$
Hence, the correct option is (c).