Question

the perimeter of a rectangle is 360m.if its length is decreasedby 20 % and breadth is increased by 25% we get same perimeter .find the dimension of the rectangle

Answer 1

Perimeter of a rectangle = 2 (length + breadth)

360 = 2(l+b) → l+b = 180

After increasing the breadth and decreasing the length, the new values of l and b are 0.8l and 1.25b.

360 = 2(0.8l+1.25b) → 0.8l+1.25b = 180

0.8l+1.25b = l+b → 0.2l = .25b → l = 1.25b

Substituting these values in the original equation, we get b = 180/2.25 = 80 m.

l = 1.25×80 = 100m.

Breadth = 80 metres and Length = 100 metres.