Question

A hall is 10 m long, 5 m wide and 4 m high. It has one door 2 m by 1 m and 2 windows 1 m by
80 cm. Find the
(i) area of the 4 walls (excluding the door and
windows)
(ii) cost of distempering the walls at 50 per m².
(iii) cost of polishing the floor at the rate of 5
per m?​

Answer 1

Answer:

Given :-

• Length of wall = 10 m
• Width of wall = 5 m
• Height of wall = 4 m
• One door of 2 m by 1 m
• Two window of 1m by 80 cm

To Find :-

1. Area of 4 walls
2. Cost of distemper ing the walls at 50 per m².
3. cost of polishing the floor at the rate of 5 per m?

Solution :-

[1]

At first we will find Area of 4 wall by

Area of wall = 2 × Height (Length + Breadth)

Area of 4 wall = 2 × 4 (10 + 5)

Area of 4 wall = 8(15)

Area of 4 wall = 120 m²

Now,

Area of 2 windows = 2(l × b)

• Breadth = 0.8 m

Area of 2 windows = 2(1 + 0.8)

Area of 2 windows = 2(0.8)

Area of 2 windows = 1.6 m²

Now,

Area of 1 door = L × B

Area of 1 door = 2 × 1

Area of 1 door = 2 m²

Total area = 120 - 1.6 - 2

Total area = 116.4 m²

[2]

Area of wall = 2 × Height (Length + Breadth)

Area of 4 wall = 2 × 4 (10 + 5)

Area of 4 wall = 8(15)

Area of 4 wall = 120 m²

Total cost = 120 × 50

Total cost = ₹ 6000

[3]

Floor include the Area of rectangle

Area = Length × Breadth

Area = 10 × 5

Area = 50 m²

Cost = 50 × 5

Cost = ₹250

Answer 2

Given -

A hall is 10 m long, 5 m wide and 4 m high. It has one door 2 m by 1 m and 2 windows 1 m by

80 cm.

To find -

• area of the 4 walls (excluding the door and windows)
• cost of distempering the walls at 50 per m².
• cost of polishing the floor at the rate of 5 per m²

Solution -

• Length of a hall = 10m
• Breadth of a hall = 5m
• Height of a hall = 4m

Area of four walls = Lateral surface area of cuboid

→ 2(length + breadth) × height

→ 2(l + b)h

→ 2(10 + 5)4

→ 2 × 15 × 4

→ 120 m²

Focus Zone : We have to find area of four walls (excluding the area of door and windows)

So, area of door and window

• Dimensions of door

→ Length of door = 2m

→ Breadth of door = 1m

• Dimensions of window

→ Length of window = 1m

→ Breadth of window = 80 cm = 80/100 = 0.8m

★ Area of door + 2 × area of windows

→ l × b + 2 × l × b

→ 2 × 1 + 2× 1 × 0.8

→ 2 + 1.6

→ 3.6m²

Now area of four walls (excluding the area of door and windows)

→ (120 - 3.6)m² = 116.4m²

_______________________________

→ Rate of distempering the walls = Rs.50

Focus Zone : Don't include area of door and windows.

→ Total cost

→ 50 × 116.4

→ Rs.5820

•°• The cost of distempering the walls = Rs.6000

________________________________

Area of the floor

→ Length × breadth

→ 10 × 5

→ 50 m²

Rate of polishing the floor = Rs.5

→ Total cost

→ 5 × 50

→ Rs.250

•°• Cost of polishing the floor = Rs.250

________________________________