Question

The length and breadth of rectangular field are in the ratio 4 :3. if the area of the field is 8112 m sq, find the cost of fencing the field with wire five at the rate of Rs. 2.85 per m.

Answer 1

let the length be 4x and the breadth be 3x

it is given that the area is 8112

area of rectangle = 8112 

(length * breadth ) = 8112

(4x*3x) = 8112

12x^2 = 8112

x^2 = 8112/12

x^2 = 676 

x= root 676

x= 26

then the length of rectangle = 4*26 = 104m and breadth = 3*26 = 78m

now,  

perimeter of the rectangle = 2(l+b)

here, perimeter of rectangle  =2(104+78)

here, perimeter of rectangle = 2*182

here, perimeter of rectangle = 364m

now, cost of fencing  = 2.85 * 364

cost of fencing with 1 wire = Rs 1037.4

Cost of fencing with 5 wires =5*1037.4 =Rs 5187

i hope this will help you 

- by ABHAY