Question

Find the cost of painting the 4 walls
of a room having length 12m breadth
10m and height 8m at the rate of 35
per m2​

Answer 1

Given :-

• Dimensions of  room  - length 12m ,breadth 10m and height 8m

To Find :-

• Cost painting four walls at the rate of 35 per m2

Solution :-

~Here, we’re given the dimensions of a room and we need to find the cost of painting it’s four walls at the rate of 35 per meter square. Firstly we need to find the curved surface area of the room and then multiply it with the cost given.

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As we know that ,

$\boxed{\sf{ \maltese \;\; CSA = 2h( l + b ) }}$

Where,  

• l is length ( 12 m )  
• b is breadth ( 10 m )  
• h is height ( 8 m )

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Finding the area to be painted :-

$\sf \implies 2 \times 8 ( 12 + 10 )$

$\sf \implies 16 ( 12 + 10 )$

$\sf \implies 16( 22 )$

$\sf \implies 16 \times 22$

$\boxed{\bf{ \bigstar \;\; CSA = 352 \;m^{2} }}$

Finding the cost :-

$\sf \implies CSA \times Cost\;per\;m^{2}$

$\sf \implies 352 \times 35$

$\boxed{\bf{ \bigstar \;\; Rs. \; 12320}}$

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Hence,  

• The cost of painting the wall is Rs. 12320

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Answer 2

Answer:

$\underline{ \underline{ \Large \pmb{\mathit{ {Given:}} }} }$

• Length of the room = 12 m

• Breadth of the room = 10 m

• Height of the room = 8 m

• Cost of painting 4 walls per m² = Rs. 35

$\underline{ \underline{ \Large \pmb{\mathit{ {To \: calculate:}} }} }$

• Total cost of painting the 4 walls of a room.

$\underline{ \underline{ \Large \pmb{\mathit{ {Calculation:}} }} }$

Here, we are given the length, breadth and the height of the room that is 12 m, 10 m & 8m. We have to find the total cost of painting the 4 walls of a room. In order to find it, we need to calculate the area of the four walls of the room. And then as the cost of painting 4 walls per m² is Rs. 35, so the total cost of painting the 4 walls of a room will be Rs. 35 times the area of the 4 walls of the room.

⠀⠀⠀⠀⠀_____________

$\longrightarrow \boxed{\sf { {Area}_{(4 \: Walls \: of \: Room)} = {L.S.A}_{(Room)} }}$

$\longrightarrow \sf { {Area}_{(4 \: Walls \: of \: Room)} = 2(l+b) \times h }$

$\longrightarrow \sf { {Area}_{(4 \: Walls \: of \: Room)} = 2(12+10) \times 8 \: {m}^{2} }$

$\longrightarrow \sf { {Area}_{(4 \: Walls \: of \: Room)} = 2(22) \times 8 \: {m}^{2} }$

$\longrightarrow \sf { {Area}_{(4 \: Walls \: of \: Room)} = 44 \times 8 \: {m}^{2} }$

$\longrightarrow \sf { {Area}_{(4 \: Walls \: of \: Room)} = 352\: {m}^{2} }$. . . . ★

Now, calculating the total cost of painting the 4 walls of a room.

$\longrightarrow \boxed{\sf { {Total \: Cost}_{( \: Painting4 \: Walls )} = {Cost}_{(1 \: {m}^{2} )} \times {Area}_{(Four \: Walls)} }}$

$\longrightarrow \sf { {Total \: Cost}_{( \: Painting4 \: Walls )} = Rs. \: ( 35 \times 352) }$

$\longrightarrow \boxed{ \pmb{\rm \red{ {Total \: Cost}_{( \: Painting4 \: Walls )} = Rs. \: 12320}}}$

Therefore, total cost of painting the 4 walls of a room is Rs. 12320 and Option A is correct.