Question

A class room is 12 m long, 10 m wide and 1.5 m high. It has two doors each 2 m long 1 m wide and 3 windows each 1.5×0.5m find the cost of painting it's four walls at Rs 12 per m
square

Answer 1

Question :-

• A class room is 12 m long, 10 m wide and 1.5 m high. It has two doors each 2 m long 1 m wide and 3 windows each 1.5m × 0.5m. find the cost of painting it's four walls at Rs 12 per m square.

Answer

★ Given :-

• A class room is 12 m long, 10 m wide and 1.5 m high.
• 2 doors each 2 m long and 1 m wide.
• 3 windows each 1.5m × 0.5m.

★ To Find :-

• Cost of painting it's four walls at Rs 12 per m square.

★ Formula used :-

• Area of rectangle = Length × Breadth
• Area of 4 walls = 2 × (Length + Breadth) × Height

★ Solution :-

★ Dimensions of Room

Length of Room, l = 12 m

Breadth of Room, b = 10 m

Height of Room, h = 1.5 m

Area of 4 walls

= 2 × (l + b) × h

= 2 × (12 + 10) × 1.5

= 3 × 22

= 66 m²

★ Dimensions of door :-

Length of Door = 2 m

Breadth of Door = 1 m

Area of 1 door = 2 × 1 = 2 m²

So, area of 2 doors = 2 × 2 = 4 m²

★ Dimensions of window :-

Length of window = 1.5 m

Breadth of window = 0.5 m

Area of 1 window = 1.5 × 0.5 = 0.75 m²

So, area of 3 windows = 0.75 × 3 = 2.25 m²

★ Required Area of room to be white - washed

= Area of 4 walls - Area of 2 doors - Area of 3 windows

= 66 - 4 - 2.25

= 59.75 m²

Cost of white - washing 1 m² = ₹ 12

So, Cost of white washing 59.75 m² = 12 × 59.75 = ₹ 717.

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Additional Information

Cuboid :-

l = Length of Cuboid

b = Breadth of Cuboid

h = Height of Cuboid

• Volume = l × b × h
• Curved Surface Area = 2 × (l + b) × h
• Total Surface Area = 2 × (l×b + b×h + h×l)
• Perimeter of Cuboid = 4 × (l + b + h)

Cube :-

• Volume = (side)³
• Curved Surface Area = 4 × (side)²
• Total Surface Area = 6 × (side)²
• Perimeter of cube = 12 × side

Answer 2

Answer:

₹648

Step-by-step explanation:

Length of classroom = 12m

breadth of classroom= 10m

height of classroom = 1.5m

Curved surface area = 2h(l+b)

= 2×1.5(12+10)

= 66m^2

Area of 3 windows= 3×(1.5+0.5)

= 6m^2

Area of two doors = 2×(2+1)

= 6m^2

Here ,

CSA - (Area of windows+ Area of doors)

= 66- (6+6)

= 54m^2

Cost of painting it's four walls at ₹12 per m^2

= 54×12

= ₹648 ans

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HOPE! IT HELPS YOU.