Question

13) The length of a room is 15 m and its breadth is double
its height. If the area of four walls of the room is 250 sq.m,
breadth of the room is:​

Answer 1

Answer:

30m

Step-by-step explanation:

Length = 15m

Breadth = 2 x height

             = 2 x 15

             = 30m

Answer 2

Answer:

Breadth of the room is 10 m.

Step-by-step explanation:

Given :

• The length of a room is 15 m.
• Breadth is double the height.
• Area of four walls of the room is 250 m².

To find :

Breadth of the room.

Solution :

Let the breadth of the room be b m, then the breadth will be double the height, i.e. b = 2h, this can be written it terms of height as h = b/2.

➤ Area of four walls means lateral surface area of room/cuboid :

• 2h(l + b)

Here,

• Area = 250 m²
• h = b/2 m
• l = 15 m
• b = b m

So,

⇛ 250 = 2 × b/2(15 + b)

⇛ 250 = 2b/2(15 + b)

⇛ 250 = 15b + b²

⇛ b² + 15b - 250 = 0

⇛ b² + 25b - 10b - 250 = 0

(25 × 10 = 250) & (+25 - 10 = +15)

⇛ b(b + 25) - 10(b + 25) = 0

⇛ (b - 10)(b + 25) = 0

⇛ b = 10 or b = -25

(Breadth cannot be negative so b = 10)

➤ ∴ Breadth of the room is 10 m.