Question

13. A room is 6.2 m long, 3.8 m wide and 3.2 m high. It has 2 doors each 2 mx 1,2 m and 2 windows
each 1.2 m x 1.5 m. Find the cost of white-washing its walls at the rate of 10 per square metre.
14. A marble tile measures 10 cm x 14 cm. How many tiles will be required to cover a wall of size
2.8 mx 4 m?
15. A rectangular room of size 5 m x 35 dm is to be carpeted with a carpet 7 dm wide. Find the length
of the carpet required.​

Answer 1

Correct Question : A room is 6.2 m long , 3.8 m wide and 3.2 m high. It has 2 doors each 2 m × 1.2 m and 2 windows each 1.2 m x 1.5 m. Find the cost of white-washing its walls at the rate of 10 per square metre.

Solution :

As given ,

The dimensions of room → 6.2m× 3.8m × 3.2m

Area of four walls , 2 ( l × b ) × h

→ 2 ( 6.2 + 3.8 ) × 3.2

→ ( 2 × 10 × 3.2 ) m²

→ 64 m²

The dimensions of Doors → 2m × 1.2m

Area , L × B

→ 2 × 1.2

→ 2.4 m²

The dimensions of windows → 1.5m × 1.2m

Area , L × B

→ 1.5 × 1.2

→ 1.8 m²

( Area of four walls ) - ( area of windows + area of doors )

⇒ 64 m² - ( 2 × 2.4 + 2 × 1.8 )m²

⇒ 64 m² - ( 4.8 + 3.6 )m²

⇒ 64m² - 8.4m²

⇒ 55.6 m²

Cost of white washing per square metre → 10 rs

Total cost → 55.6 × 10 = 556 rs

Question : A marble tile measures 10 cm x 14 cm. How many tiles will be required to cover a wall of size 2.8 m × 4 m ?

Solution :

Dimensions of wall → 2.8 m × 4 m

Area → 11.2 m²

Dimensions of tile → 10 cm × 14 cm

Area → 140 cm²

⇒ 11.2 m² into cm²

⇒ 1 m² → 100 × 100 cm²

⇒ 11.2 m² → 11.2 × 10000

⇒ 112000 cm²

Number of tiles =

112000 cm² / 140 cm²

→ 800 tiles

Question : A rectangular room of size 5 m x 35 dm is to be carpeted with a carpet 7 dm wide. Find the length of the carpet required.

Solution :

Dimensions of room → 5m × 35dm or 3.5m

Area → 17.5 m²

Area of carpet = Area of room

Length × 7 dm or 0.7 m = 17.5 m²

Length × 0.7 m = 17.5 m²

Length = 17.5 m² / 0.7 m

Length = 25 m