Question

The sides of rectangle are in ratio 4 ∶ 3.If its area is 1728m' Find the cost of fencing at Rs. 30 per m2 [Rs. 5040]

Answer 1

so let the sides as 4x and 3x
now,

4x+3x=1728$cm^2$

12$x^2$=1728

$x^2= \frac{1728}{12}$

$x^2= 144$

$x= \sqrt{144}$

$x=12 \:cm^2$

now perimeter would be
2(3×12+4×12)
=2(88)
=176 cm

cost of fencing
=176×30
=₹5280

Answer 2

Let the dimensions be 4x and 3x

Given area= 1728m^2

Area of rect. = l*b

1728 = 4x*3x

1728=12x^2

1728/12= x^2

144 = x^2

12 = x

So lenght =4x =4*12 =48m

Breadth =3x =3*12 = 36m

Cost of fencing = ₹30/m

Perimeter of rect = 2(l + b)

=2(48+36)

=2*84

=168m

Cost of fencing = ₹( 30*168)

=₹5040