Question

If the length and breadth of a rectangular plot are
each increased by 1m, then the area of the floor
is increased by 21 sq. m. If the length is increased
by 1 m and breadth is decreased by 1m, then the
area is decreased by 5 sq.m. What is the perimeter
of the floor?
(1) 30m (2) 32m (3) 36m (4) 40m​

Answer 1

Answer:

Let the length of plot be x m and breadth be y m.

Then area of plot = length×breadth = xy sq.m

Case 1

Length and breadth are increased by 1m each

Area = (x+1)(y+1) = xy+y+x+1 = xy+21

= x+y+1 =21

= x+y = 21-1 = 20 m

So perimeter of the floor = 2(x+y)

= 2×20 = 40m

Answer = 4) 40m