Question

The walls and the roof of a room 10 ft in length, 8ft in width and 10 ft in height is to be painted. How much will it cost at rs 5 per square ft?

Answer 1

Given :

• Length of room = 10 ft
• Width of room = 8ft
• Height of room = 10ft
• Walls and roof is to be painted
• Rate of painting = Rs 5/ft²

To find :

• Cost of painting wall and roof

Formula used :

• Area of rectangle = length × width
• Lateral surface area of cuboid = 2× height × ( length + breadth )

Solution :

First of all we need to find area of 4 walls and roof , then we will add those area. To find cost of painting we will multiply total area with rate of painting.

Total area to be painted = Area of 4 wall + area of roof

➝ Total area to be painted = Lateral surface area of room + Area of roof

➝ Total area to be painted = [ 2 × 10ft × ( 10ft + 8ft) ] + ( 10ft × 8ft)

➝ Total area to be painted = [ 20ft × 18ft ] + 80ft²

➝ Total area to be painted = 360ft² + 80ft²

➝ Total area to be painted = 440 ft²

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Cost of painting = Rate of painting × Total area to be painted

➝ Cost of painting = Rs 5/ft² × 440 ft²

➝ Cost of painting = Rs 2200

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ANSWER : Rs 2200

Answer 2

Given Question :-

• The walls and the roof of a room 10 ft in length, 8ft in width and 10 ft in height is to be painted. How much will it cost at rs 5 per square ft?

ANSWER

GIVEN -

• Length of room = 10 ft.

• Breadth of room = 8 ft.

• Height of rom = 10 ft.

TO FIND -

• Cost of painting the roof and four walls at Rs 5 per square feet.

Formula Used -

$\boxed{ \pink{ \bf \: Area_{(roof)} = Length \times Breadth}}$

$\boxed{ \purple{ \tt \: Area_{(four \: walls)} = 2(Length + Breadth) \times height}}$

$\large\underline\purple{\bold{Solution :- }}$

Given that

• Length of room = 10 ft.

• Breadth of room = 8 ft.

• Height of rom = 10 ft.

So,

• Total area to be painted is given by

$\rm :\implies\: = Area_{(roof)} + Area_{(four walls)}$

$\rm :\implies\: = 10 \times 8 + 2(10 + 8) \times 10$

$\rm :\implies\: = 80 + 20 \times 18$

$\rm :\implies\: = 80 + 360$

$\rm :\implies\: = 440 \: square \: feet$

So,

$\rm :\implies\:Cost \: of \: 1 \: sq. \: feet \: = Rs \: 5$

$\rm :\implies\:Cost \: of \: 440 \: sq. \: feet \: = Rs \: 5 \times 440 = Rs \: 220$