Question

A rectangular room of dimension 8 m X 6 m X 3 m is to be painted. If it costs 60 per square
metre, find the cost of painting the walls of the room.



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Answer 1

Given:-

• Length = 8m

• Breadth = 6m

• Height = 3m

• Cost of painting = Rs. 60/m²

To Find:-

• Cost of painting the walls of the room

Formula used:-

• Lateral Surface Area of Cuboid = 2h ( l + b )

Solution:-

Area of Four walls = Lateral Surface Area

Then,

⟾ Lateral Surface Area of Cuboid

= 2h ( l + b )

⟾ Lateral Surface Area of Cuboid

= 2×3 ( 8 + 6 )cm²

⟾ Lateral Surface Area of Cuboid

= 6 × 14 cm²

⟾ Lateral Surface Area of Cuboid

= 84 cm²

Hence, the area of four walls of the rectangular room is 84 cm².

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Finding the cost of painting the walls:-

⟾ Cost of Painting = Rs. 84 × 60

⟾ Cost of Painting = Rs. 5040

Hence, the cost of painting the walls of the rectangular room is Rs. 5040.

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Answer 2

Answer :

• Cost of painting the walls of the room is Rs.5040

Given :

• A rectangular room of dimension 8m × 6m × 3m is to be painted
• It costs 60 per square m

To find :

• Cost of painting the walls of the room

Solution :

Given,

• Length of a room = 8m
• Breadth of a room = 6m
• Height of a room = 3m

As we know that,

Area of four walls of a room is the lateral surface area of room where cuboid

• Lateral surface area of room = 2(l + b) × h

Where,

• L is length
• b is breadth
• h is height

》Lateral surface area of room = 2(l + b) × h

》2(8 + 6) × 3

》2(14) × 3

》28 × 3

》84m²

Hence, Area of the four rooms is 84m²

Now, Also Given that,

• Cost 60 per square m

Then,

• Cost of painting the walls of the room = Area of four rooms × Cost of painting per square m

》84 × 60

》5040

Hence , Cost of painting the walls of the room is Rs.5040