Question

The area of four walls of a room is 120 m2. If the length of the room is twice its breadth and the height is 4 m. Find the area of the floor.

Answer 1

Let breadth of the room = b m
Length= 2b m
Height= h= 4m
1) area of the four walls of the room = 2(length+breadth)*h
2(2b+b)*4=120m^2
8*3b=120
b=120/(8*3)
b=5m
Therefore
Breadth=b=5m
Length=2b=2*5=10m
2)area of the floor= length*breadth
=10m*5m
=50m^2

Answer 2

Let the length and breadth of the room be 2x and x respectively.
Then,
CSA=2h(l+b)
120=2×4(2x+x)
120=8×3x
120=24x
120/24=x
x=5
2×Length=breadth
10=5
TSA=2(lb+BH+hl)
=2(10×5+5×4+4×10)
220m².
TSA-CSA=Area of floor+Area of ceiling
100m².
Area of floor=100/2
Area of floor=50m².