Q4 of 28 Page 133

The sides of a rectangular park are in the ratio 4:3. If the area is1728 m2, find the cost of fencing it at the rate of Rs. 2.50/m.

Let us consider a Rectangle ABCD,



According to the problem, it is given that


The sides are in the ratio 4:3.


The area of Rectangle is 1728m2.


The cost of fencing is Rs.2.50/m.


Let us consider the length(L) of the Rectangle be ‘4x’m and the breadth(B) of the rectangle be ‘3x’m.


We know that Area(A) of a Rectangle is


A = L × B


From the given data we can write,


4x × 3x = 1728


12x2 = 1728



x2 = 144


x = √144


x = 12


Now we find the length and breadth of the triangle.


Length(L) = 4x


L = 4 × 12


L = 48m


Breadth(B) = 3x


B = 3 × 12


B = 36m


To find the total cost for fencing, we need to find the perimeter first.


As we know that the fencing the sides of the rectangle but not total internal part of the rectangle.


Now, let’s find the Perimeter (P) of the rectangle.


We know that Perimeter(P) of the Rectangle is


P = 2 × (L + B)m


Now let’s substitute the values of length and breadth of the rectangle.


P = 2 × (48 + 36)


P = 2 × (84)


P = 168m


The total cost required for fencing(Fc) = Perimeter*cost per meter


Fc = 168 × 2.50


Fc = 420


The total fencing cost required is Rs.420.


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