Question

A rectangular field has length three times the breadth and the perimeter is 800m. Find the cost of digging the ground at Rs8 per meter^2.​

Answer 1

Rs240 000

Explanation:

Let the length and breadth of the rectangular field be represented by l and b respectively.

Thus,

l = 3b ............. 1

Perimeter of a rectangle = 2(l + b)

The perimeter of the given rectangle = 800 m, so that;

800 = 2(l + b)

l + b =
`(800)/(2)`

= 400

l + b = 400 ............... 2

But, l = 3b. So that,

3b + b = 400

4b = 400

b =
`(400)/(4)`

= 100

b = 100 m

l = 3b

= 3 x 100

l = 300

The length of the rectangular field is 300 m, while its breadth is 100 m.

Area of the rectangular field = l x b

= 300 x 100

= 30 000

Area of the rectangular field is 30 000
`m^(2)`.

Cost of digging the ground at the rate of Rs8 per
`m^(2)` = Rs8 x 30 000

= Rs240 000