Question

16) A room is of length 6 m , width 4m and height6 m find the cost of whitewashing four walls at the cost of rs8.50 per m^2​

Answer 1

Answer:

Area to be whitewashed = area of four walls + area of ceiling

Formulas to be noted :−

Area of four walls =2 ( length + breadth ) × height

Area of ceiling = area of rectangle = length × breadth

In the question, length of the room =6m

breadth of the room =4.5m

height of the room =3m

On the basis of formulas given above :−

Area of four walls =2(6m+4.5m)x3m

Area of four walls =2(10.5m)x3m

Area of four walls =21mx3m

Area of four walls =63m

2

Area of ceiling =6m×4.5m

Area of ceiling =27m

2

Therefore, area to be whitewashed =63m

2

+27m

2

Answer 2

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Area to be whitewashed = area of four walls + area of ceiling

Formulas to be noted :−

Area of four walls =2 ( length + breadth ) × height

Area of ceiling = area of rectangle = length × breadth

In the question, length of the room =6m

breadth of the room =4.5m

height of the room =3m

On the basis of formulas given above :−

Area of four walls =2(6m+4.5m)x3m

Area of four walls =2(10.5m)x3m

Area of four walls =21mx3m

Area of four walls =63m

2

Area of ceiling =6m×4.5m

Area of ceiling =27m

2

Therefore, area to be whitewashed =63m

2

+27m

2

Area to be whitewashed =90m

2

Cost of whitewashing = rate at which area is being whitewashed × area to be whitewashed

Cost of whitewashing =Rs8/m

2

×90m

2

Cost of whitewashing =Rs8×90

Cost of whitewashing =Rs.720.