Question

A rectangular room is 4.5 m long, 4 m wide and 3 m high. Find the cost of white washing its walls and roof at ₹7.50 per m2.

Answer 1

Answer:

The cost of white washing the walls of the room is ₹ 517.5

Step-by-step explanation:

It is given that the rectangular room is 4.5 m long, 4 m wide and 3 m high.

So,

Length of the room = 4.5 m

Breadth of the room = 4 m

Height of the room = 3 m

We know( formula ),

Area of four walls = 2( l + b )h , where l is the length of the cuboid, b is the breadth of the cuboid and h is the height of the cuboid.

Now,

Area of its walls = 2( 4.5 m + 4 m )3 m

                 ⇒ 2( 8.5 m )3 m

                 ⇒ 6 x 8.5 m^2

                 ⇒ 51 m^2

And, area of roof = length x breadth  

                  ⇒ 4.5 m x 4 m

                  ⇒ 18 m^2

Now, area to be whitewashed = 51 m^2 + 18 m^2 = 69 m^2

Therefore,

Cost of white washing the walls = Rate of white washing x area to be white washed

Cost of white washing the walls = Rs 7.5 / m^2 x 69 m^2

Cost of white washing the walls = Rs 7.5 x 69

Cost of white washing the walls = Rs 517.5

Answer 2

perimeter of floor = 2( length + breadth)

As Area of four walls = perimeter of floor × height

= 2( l+ b) h

As l = 4.5 m

b= 4 m

h= 3m

So Area = 2( 4.5 + 4) ×3

= 2× 8.5 ×3

= 17× 3

= 51 m^2

Area of roof = area of floor = length × breadth

= 4.5× 4= 18 m^2

So area of walls + roof = 51 +18= 69 m^2


As Cost of white washing is 7.5 per m^2

So 69 m^2 cost is 69× 7.5= 517.5 rs


✌✌✌✌✌Dr.Dhruv✌✌✌✌