Question

the area of a rectangular field is 4 hectare. Find its lenght if the brdadth is 160m. Also, find the cost of fencing its boundary at the rate of 5.20 per metre.

Answer 1

The basic idea of the question is determining the length from given area and breadth,
Then applying the length and breadth to find the perimeter and then the cost.

Now, you should know one thing that all the units in a question should be same but here the area is in hectare and the rest in metre.
So we need to convert to same unit.
Now,
$1hectare = 10000 {m}^{2}$
So with this the area becomes
$40000 {m}^{2}$
So, the question is now easy...
Check the above photograph for the used process..
Hope this will be helping you.

WARM REGARDS
Sahil khirwal

Answer 2

given breadth of rectangular plot=160m
area=4*10000m^2=40000m^2
let length=lm
then,area=length*breadth=l*160
~40000=l*160
~l=250m
then boundary length=2(l+b)=2(250+160)=820m
given,
cost for 1m------------5.20
cost for 820m------------?(x)
then cost for fencing boundary==(5.2)*820=4264