Question

Length and breadth of a rectangular field are in the ratio 5 ratio 4 if the perimeter of the field is 810 cm, then find its length and breadth in metres

Answer 1

Given the ratio between length and breadth as
$\frac{l}{b} = \frac{5}{4}$
It can be written as :
$\frac{l}{b} = \frac{5 \times x}{4 \times x}$
where x is an arbitrary constant

So , we now have :
$l = 5 \times x$
$b = 4 \times x$
and so applying the perimeter formula ,
l+b = perimeter, we get

l + b = 810
or, 5x + 4x = 810
or 9x = 810
or x = 90

from this, l and b can be calculated as :
l = 5x = 5×90 = 450cm
b= 4x = 4×90 = 360cm