Question

the length,breadthand height of a room are 5m,4m,3m,resp.find the cost of whitewashing wallsof the room at the and the caulking at the rate of RS 7.50sqm​

Answer 1

Answer :

›»› The cost of white-washing wall of the room is Rs. 555 m².

Step-by-step explanation :

Given :

• Length of a room = 5 m.
• Breadth of a room = 4 m.
• Height of a room = 3 m.

To Find :

• The cost of white-washing wall of the room.

Formula required :

Formula to calculate the area of rectangle is given by,

→ Area of rectangle = l × b.

Here,

• l is the length.
• b is the breadth.

Units,

• The unit of length is m.
• The unit of breadth is m.

Formula to calculate the total surface area of cuboid is given by,

→ TSA of cuboid = 2(lb + bh + hl).

Here,

• l is the length of room.
• b is the breadth of room.
• h is the height of room.

Units,

• The unit of length is m.
• The unit of breadth is m.
• The unit of height is m.

Solution :

First we will find area of floor.

Since floor is always is in the shape of rectangle.

We know that, if we are given with the length and breadth then we have the required formula, that is,

→ Area of rectangle = l × b

→ Area of rectangle = 5 × 4

→ Area of rectangle = 20.

∴ The area of floor is 20 m².

Now,

We know that, if we are given with the length of room, breadth of room and height of room the. we have the required formula, that is,

→ TSA of cuboid = 2(lb + bh + hl).

By using the formula to calculate the total surface area of cuboid and substituting all the given values in the formula, we get :

→ TSA of cuboid = 2{(5 × 4) + (4 × 3) + (3 × 5)}

→ TSA of cuboid = 2{20 + (4 × 3) + (3 × 5)}

→ TSA of cuboid = 2{20 + 12 + (3 × 5)}

→ TSA of cuboid = 2{20 + 12 + 15}

→ TSA of cuboid = 2{32 + 15}

→ TSA of cuboid = 2 × 47

→ TSA of cuboid = 94.

∴ The area of room is 94 m².

Now,

Area of room without floor = Area of room - Area of floor

→ Area of room without floor = 94 - 20

→ Area of room without floor = 74.

∴ The area of room without floor is 74 m².

Now,

Cost of white-washing of the room = Area of room without floor × 7.50.

→ Cost = 74 × 7.50

→ Cost = 555

Hence, the cost of white-washing wall of the room is Rs. 555 m².

Answer 2

Given :-

Length of room = 5 m

Breadth of room = 4m

Height of room = 3 m

To Find :-

Total cost

Solution :-

Firstly we will find Area of room

$\tt Area = l \times b$

$\tt Area = 5 \times 4$

$\tt Area = {20 m}^{2}$

Now

Let's find TSA of cuboid

$\tt TSA = 2(lb + bh + lh)$

$\tt TSA = 2(5 \times 4 + 4 \times 3 + 3\times 5)$

$\tt TSA = 2(20 + 12 + 15)$

$\tt TSA = 2(47)$

$\huge \bf TSA = 94 M$

$\tt Area \: of \: room \: without \: floor = TSA - Area$

$\tt Area \: without \: floor = 94 - 20$

$\tt Area \: without \: floor = 74 m$

$\tt Total \: Cost = 74 \times 7.50$

$\huge \fbox {Total \: cost = 555 \: Rupees }$