The length, breadth and height of a room are 5 m, 4 m and 3 m respectively. Find the cost of white-washing the walls of the room and the ceiling at the rate of Rs.7.50 per m2.

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Rs. 600

Rs. 555

Rs. 650

Rs. 560

answer is A.

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Detailed Solution

Given, the dimensions of the room,
Length = 5m,
breadth = 4m,
Height = 3m.
Total Surface area of the room is the area of four walls, area of the roof or ceiling and the area of the floor of the room.
Total Surface Area of the cuboid is,

2 (l b + b h + h l)

⇒

2 (5 × 4 + 4 × 3 + 3 × 5)

⇒ 2 (20 + 12 + 15)

⇒ 2 (47)

⇒ 94 m 2

The area of the floor is not getting white- washed.
So, it will be subtracting.
The area which needs to be white washed

⇒ 94 − 5 × 4

⇒ 94 − 20

⇒ 74 m 2

The cost of whitewashing is

⇒ 74 × 7.50

⇒ R s .555

Therefore, the correct option is 1.

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