Question

6. The dimensions of a room are 5 mx 4m x 3 m. Find the cost of white washing the walls of the room and the ceiling at the rate of 111.5 per m.​

Answer 1

$\bold { Question}$

The length, breadth and height of a room are 5 m, 4 m, and 3 m respectively. Find the cost of white washing the walls of the room and ceiling at the rate of ₹111.5 per m2.

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$\bold{Solution}$

Given:

• Length of a room is 5 m
• Breadth of a room 4 m
• Height of a room 3 m

Since the four walls and ceiling are to be whitewashed so, it has 5 faces.Hence, the area of the room to be whitewashed

$\tt {Lateral \: surface \: area \: of \: cuboid =} \red {2(l + b)h}$

• Length, l = 5 m
• Breadth, b = 4 m
• Height, h = 3 m

Surface area of 5 faces

$\tt→Area \: of \: 5 \:faces = lb + 2(l + b)h$

$\tt→lb + 2(l + b)h = (5 m × 4 m) + 2 × (5 m + 4 m) × 3 m$

$\tt → 20 m² + 2 × 9 m × 3 m$

$\tt→ 20 m² + 54 m2$

$\tt→74 m²$

The cost of whitewashing the walls of the room and ceiling = Rate × Area

$\tt→₹ 111.5/ m² × 74 m2$

$\tt→₹ 8251$

• Cost of whitewashing the walls of the room and the ceiling is ₹8251.

Answer 2

Answer:

The dimensions of a room are 5 mx 4m x 3 m. Find the cost of white washing the walls of the room and the ceiling at the rate of 111.5 per m.