Question

- The ratio of length, breadth and height of a big room is
5: 3:2 and its total surface area is 1550 m. Find the
dimensions of the room. Also find the cost of white
washing the four walls and ceiling of the room at the
rate of 6.95 per m.​

Answer 1

Let the length,breadth and height be x.

L=5x

B=3x

H=2x

As we know,the total surface area of a room(cuboid)=2(lb+bh+lh)sq units.

A/Q=2(5x×3x+3x×2x+5x×2x)=1550m

2(15x+6x+10x)=1550m²

2×31x=1550m²

62x=1550m²

x=1550/62

=25m

Now,the value of x=25m

Then,

L=5×25=125m

B=3×25=75m

H=2×25=50m

Area of the 4 walls and ceiling of the room=2(l+b)×h

=2(125+75)×50

=2×200×50

=20000m²

Cost of white washing the walls and ceilings of 1m²=6.95

Cost of white washing the walls and ceilings of20000m²=20000×6.95

=139000

Hence,the dimensions of room are=125m,75m,50m.

and the cost of white washing the four walls and ceiling of the room is rupee 139000.