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प्रश्न
The dimensions of a room are 12.5 m by 9 m by 7 m. There are 2 doors and 4 windows in the room; each door measures 2.5 m by 1 .2 m and each window 1 .5 m by I m. Find the cost of painting the walls at Rs. 3.50 per square metre.
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उत्तर
Given length of room =12.5m
Breadth of room = 9m
Height of room = 7m
∴Total surface area of 4 walls
`=2(l+b)xxh`
`=2(12.5+9)xx7`
`=30lm^2`
Area of 2 doors `=2[2.5xx1.2]`
`= 6 m^2`
Area to be painted on 4 walls
`= 301-(6+6)`
`=301-12=289 m^2`
`∴ "cost of painting" = 289 xx 3.50 `
`Rs.1011.5`
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