Question

The length breadth and hight of a room are 5m, 4m and 3m Repectively. Find the cost of white washing the wall of room and the ceiling at the rate of ₹7.50 per m².​

Answer 1

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Curved surface area of cuboid = 2h(l +b)

CSA of room = 2 × 3(5 + 4)m

CSA of room = 6(9)m

CSA of room = 54m³

Since, ceiling is in the shape of rectangle we will use the formula of area of rectangle.

Area of ceiling = L × B

Area of ceiling = 5 × 4m

Area of Ceiling = 20m²

Area of the whitewashing the room + ceiling = Area of four walls + Area of ceiling

Area of whitewashing the room= 54 + 20m = 74m³

Cost of whitewashing the wall and ceiling of room = Area of room × cost given

Cost of whitewashing the wall and ceiling = 74 × 7.50 = ₹555 Ans.

Answer 2

Answer:

Use formula 2(lb + bh +hl) and subtract area of floor then multiply by 7.5 and you get your answer

Answer is Rs. 555