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Question
The cost of preparing the walls of a room 12 m long at the rate of Rs. 1.35 per square metre is Rs. 340.20 and the cost of matting the floor at 85 paise per square metre is Rs. 91.80. Find the height of the room.
Solution
Given that
Length of room = 12m.
Let height of room be ‘h’ m.
Area of 4 walls = 2 (l + b)x h
According to question
`⇒2(l+b)xxhxx1.35=340.20`
`⇒2(12+b)xxhxx1.35=340.20`
`⇒(12+b)xxh=(170.10)/1.35=126 .......(1)`
Also area of floor = l x b
`∴lxxbxx0.85=91.80`
`⇒12xxbxx0.85 = 91.80`
`⇒b=9m`
Substituting b= 9m in equation (1)
`⇒(12+9)xxh=126`
`⇒h=6m`
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