Question

A classroom 7m long ,6.5m wide, 4m high. It has one door 3m*1.4m and yhree windows measuring 2m*1m. The interior walls are to be colour washed. The painter charges Rs.15 persq.m . Find the cost of colour washed
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Answer 1

Area of four walls = 2h(l + b)

Given that -

• length of room = 7m
• breadth of room = 6.5m
• height of room = 4m

Substitute the known values in above formula

=> 2(4)[7 + 6.5]

=> 8(13.5)

=> 108 m²

Area of one window = length × breadth

Given that -

• length = 3m
• breadth = 1.4m

Substitute the known values in above formula

=> 3 × 1.4

=> 4.2 m²

Area of three window = length × breadth

Given that -

• length = 2m
• breadth = 1m

Substitute the known values in above formula

=> 2 × 1

=> 2 m²

Now,

Total area of window = Area of one window + Area of three window

=> 4.2 + 2

=> 6.2 m²

Also,

Area of white washing = Area of four walls - Total area of windows

=> 108 - 6.2

=> 101.8 m²

•°• Cost of white washing at Rs. 15 per m²

=> 101.8 × 15

=> Rs. 1527

Answer 2

Answer:

Step-by-step explanation:

Given :-

Dimension of Room :-

length  = 7m

breadth  = 6.5m

height  = 4m

Dimension of window :-

length = 3 m

breadth = 1.4 m

To Find :-

Cost of colour washed

Formula to be used :-

Area of four walls = 2h(l + b)

Area of one window = length × breadth

Solution :-

Putting all the values, we get

Area of four walls = 2h(l + b)

⇒ Area of four walls = 2(4)[7 + 6.5]

⇒ Area of four walls = 8(13.5)

⇒ Area of four walls = 108 m²

Area of one window = length × breadth

⇒ Area of one window = 3 × 1.4

⇒ Area of one window = 4.2 m²

Total area of window = Area of one window + Area of three window

Total area of window = 4.2 + 2

Total area of window = 6.2 m²

Area of white washing = Area of four walls - Total area of windows

Area of white washing = 108 - 6.2

Area of white washing = 101.8 m²

Cost of white washing at Rs. 15 per m²

Cost of white washing = 101.8 × 15

Cost of white washing = Rs. 1527