Question

The length ,breadth,height of a room are 5 m,4m 3 m find the cost of white washing the walls of room and ceiling at the rate of 7.50 per meter square

Answer 1

Given :-

• The length ,breadth,height of a room are 5 m,4m 3 m

To find :-

• The cost of white washing the walls of room and ceiling at the rate of 7.50 per meter square.

Solution :-

• Length of room = 5m

• Breadth of room = 4m

• Height of room = 3m

As we know that

→ Lateral surface area of cuboid = Area of four walls

Now,

→ Lateral surface area of room

→ 2(length + breadth)height

→ 2(l + b)h

→ 2(5 + 4)3

→ 2 × 9 × 3

→ 18 × 3

→ 54 m²

Area of ceiling

→ length × breadth

→ l × b

→ 5 × 4

→ 20m²

Total area of white washing

→ Area of four walls + area of ceiling

→ 54 + 20

→ 74 m²

• The cost of white washing the walls of room and ceiling at the rate of 7.50 per meter square.

Total cost of white washing

→ 74 × 7.50

→ Rs.555

Hence,

• Total cost of white washing is Rs.555

Answer 2

Answer:

Given:-

• Length of the room = 5 m
• Breadth of the room = 4 m
• Height of the room = 3 m

To find:-

Cost of white washing the walls of the room and ceiling at the rate of Rs 7.50 per sq m.

Solution:-

We know that,

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

So, Area of four walls of the room = 2h(l + b)

= 2 × 3(5 + 4)

= 6(5 + 4)

= 6 × 9

= 54 m$^{2}$

Now, area of the ceiling = l × b

= 5 × 4 = 20 cm$^{2}$

So, total area of the four walls and the ceiling of the room = 54 + 20 = 74 cm$^{2}$

Since cost of whitewashing per sq m is 7.50 Rupees.

So, total cost of white washing the four walls and ceiling of the room = 74 × 7.50

= Rs 555.