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rate problem

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rate problem

by rtaha2412 » Tue Jan 04, 2011 1:42 pm
Water flows into an empty tank of 54 liters via 12 small pipes. The rate of flow in each pipe is 1 liter per hour. However, water also flows out of the tank via several large pipes at the rate of 1.5 liter per hour. If the tank is completely full after 12 hours, how many large pipes are there?

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by Tani » Tue Jan 04, 2011 2:02 pm
54 liters filled in 12 hours = net fill rate = 4.5 liters per hour.

Small pipes (incoming) 12 pipes at 1 liter each = 12 liters incoming.

Net = incoming (12) minus outgoing (x) = 4.5

Therefore, outgoing rate = 7.5

At 1.5 per hour per large pipe, 7.5/1.5 = 5 large pipes.
Tani Wolff
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