Question

the length and breadth of a rectangular field are in ratio 5:3 the area of the field is 2160 square.m if a fence is to be made at the rate of ruppes 350 per metre how much will it cost

Answer 1

Let the common ratio between length and breadth be x.
Then, length = 5x m
          breadth = 3x m
Therefore, area = 5x × 3x = 15x²
                or, 2160 = 15x²
               or, x² = 2160/15
               or, x = √144 = 12

Therefore, length = 5×12 = 60 m
and breadth  = 3×12 = 36 m.

Perimeter of the field = 2 × (60+36) = 192 m

(Fencing means bordering the field so we need to find the perimeter)

Now, Total cost = 350 × 192 = Rs. 67200.

Answer 2

L=5x
B=3x
Lxb=area of rectangle
2160=15x²
2160/15=x²
144=x
12=x
12x5=60
12x3=36
2(60+36)=192
350x192=67,200
Therefore, it will cost 67, 200 RS.

Pls thank me and hope it will help for 7,8 graders. ☺️