Question

the ratio of the length to breadth of a rectangular lawn 3:5. it costs rs 3200 to fence at the rate of rs2 a meter what would be the cost of developing the lawn at the rate of rs 10 per square meter​

Answer 1

Cost of 2 m= 1m
Cost of 1 m= 1/2 m
Cost of 3200 m= (1/2 * 3200) m.
= 1600 m
According to problem,
Let the length be 3x and breadth be 5x
2(length +breadth) =1600 m
=> 2(3x+5x) = 1600 m
=> 2*8x = 1600 m
=> 16x = 1600 m
=> x = (1600/16) m
=> x= 100m
Therefore, length= 3x=(3*100)m =300m
Breadth= 5x=(5*100)m =500m
Area of the rectangle= l*b
= (300*500) Sq. m
= 15000 Sq. m
1 Sq. m costs= Rs. 10
15000 Sq. m costs= Rs. (15000*10)
= Rs. 150000
Ans:- Rs. 150000

Answer 2

Perimeter 3200/2

1600 m

let the length be 3x and breadth be 5x

perimeter = 1600

2(l+b). =1600

2(3x+5x)=1600

6x+10x=1600

16x = 1600

x =1600/16

100

length = 3*100

300m

breadth = 5*100

500 m

Area of rectangle = l*b

300*500

150000 m

per rate = 10 rupees

cost of developing lawn = 150000*10

1500000 rupees