Question

18. Our local club room is square in shape of side 15 m long, and 5 m high. There
are 4 doors in the club room each 1.5 m wide and 2 m high. Let's calculate the cost of
oil painting its 4 walls without doors at Rs. 350 per sq m.​

Answer 1

Given that:

• Our local club room is square in shape of side 15 m long and 5 m high.
• There are 4 doors in the club room each 1.5 m wide and 2 m high.

To Find:

• The cost of oil painting its 4 walls without doors at Rs. 350 per sq m.

We know that:

• Area of walls = 2(L + B)H

Where,

• L = Length
• B = Breadth
• H = Height

We have:

Room is square in shape so,

• L = B = 15 m
• H = 5 m

Finding the area of four walls:

Area of four walls = 2(15 + 15)5

Area of four walls = 2 × 30 × 5

Area of four walls = 300

∴ Area of four walls = 300 m²

Finding the area of 4 doors:

Area of one door = 1.5 × 2

Area of 4 doors = 4 × 1.5 × 2

Area of 4 doors = 12

∴ Area of 4 doors = 12 m²

Finding the area for painting:

Area = Area of walls - Area of doors

• Area = 300 m² - 12 m²
• Area = 288 m²

Finding the cost of oil painting:

1 m² of painting cost = Rs 350

288 m² painting cost = Rs 350 × 288 = Rs 100800

Hence,

• The cost of oil painting its 4 walls without doors is Rs 100800.

Answer 2

Given :-

Our local club room is square in shape of side 15 m long, and 5 m high. There

are 4 doors in the club room each 1.5 m wide and 2 m high.

To Find :-

Calculate the cost of  oil painting its 4 walls without doors at Rs. 350 per sq m.​

Solution :-

We know that

Area of 4 walls = LSA of cuboid = 2(l + b)h

2(15 + 15)5

2(30)5

300 m²

Area of 4 doors = Area of one door × 4

Area of one door = 1.5 × 2

Area of one door = 3 m²

Now

Area of 4 doors = 3 × 4

Area of 4 doors = 12 m²

Now

Remaining area = 300 - 12

Remaining area = 288 m²

Cost = Rate × Area

Cost = 350 × 288 =  100800

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