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Probability

Question
CBSEENMA9003368

The floor of a rectangular hall has a perimeter 250 m. If the cost of painting the four walls at the rate of ` 10 per m2 is ` 15000, find the height of the hall. [Hint : Area of the four walls = Lateral surface area.] 

Solution

Let the length, breadth and height of the rectangular hall be l m, b m and h m respectively.
Perimeter = 250 m
⇒ 2(l + b) = 250
⇒    l + b = 125    ...(1)
Area of the four walls
             space space space space space space space space space space space equals 15000 over 10 equals 1500 space straight m squared
rightwards double arrow space space 2 left parenthesis straight l plus straight b right parenthesis straight h equals 1500
rightwards double arrow space space left parenthesis straight l plus straight b right parenthesis straight h equals 750
rightwards double arrow space space 125 space straight h space equals space 750 space space space space space space space space space space space space space vertical line space Using space left parenthesis 1 right parenthesis
rightwards double arrow space space space space straight h equals 750 over 125
rightwards double arrow space space space straight h space equals space 6 space straight m
Hence, the height of the hall is 6 m.

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