Question

the total area of four walls of a room is 660 metre square and the length is twice its width. if the height of the room is 11 metre, then the area of its ceiling is

Answer 1

Given:

Area of 4 walls= 660 m²

Height (h)= 11 m

Let the width be = b m

Length (l)= 2b m

Area of 4 walls of a room = 2(l+b)×h

660 = 2 (2b+ b ) × 11

660 = 2(3b) ×11

3b = 660 / 11× 2= 60/2= 30

3b = 30

b= 30/3= 10

b= 10 m

L = 2b = 2× 10= 20 m

L = 20 m

Area of ceiling = l × b

Area of ceiling= 20 × 10 = 200 m²

Hence, the area of ceiling is 200 m²

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Hope this will help you....

Answer 2

Solution :-

As per the question -

Length of the room is twice its width. 

Let the width of the room be 'x' metre

So, the length will be = 2x metre

Then, according to the question.

Area of four walls of the room = Lateral surface area of the room

Lateral surface area of the room = 660 m² and Height = 11 m

Lateral surface area of a cuboid = 2h*(l + b)

⇒660 = 2*11*(2x + x)

⇒ 660 = 22*3x

⇒ 66x = 660

⇒ x = 660/66

⇒ x = 10 m

So, width is 10 m

Then, length = 2*10 = 20 m

Now, area of the ceiling = Length*Width

⇒ 20*10

= 200 m²

So, area of the ceiling is 200 m²

Answer.