Question

Length, breadth and height of a room are 7m, 4m and 3m respectively. It has
a door and a window of dimensions 2mxl-m
and l-xlm respectively.
Find the cost of white washing the walls and ceiling of the room at the rate
of 20 per m​

Answer 1

Dimensions of a room :

Length (L) = 7 m , Breadth (B) = 4 m,

Height (H) = 3 m

Area of four walls of a room = 2(L+B)H

= 2( 7 + 4 )× 3

= 2 × 11 × 3

= 66 m² ---(1)

ii ) Area of the ceiling = L × B

= 7 m × 4 m

= 28 m² -----(2)

Dimensions of a door:

Length = 2 m , breadth = 1 m

Area of the door = 2 m × 1 m = 2 m² ---(3)

Dimensions of a window :

Length = 1 m , breadth = 1 m

Area of the window = 1 m × 1 m = 1 m² ---(4)

Area of washing wall = (1) + (2) - (3) - (4)

= 66 m² + 28 m² - 2 m² - 1 m²

= 94 m² - 3 m²

= 91 m²

Cost of white washing 1 m² = Rs 20

Cost of washing the walls of the room = 20 × 91

= Rs 1820

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