SOLUTION: An empty swimming pool can be filled in 5hrs. When full, the pool can be drained in 17hrs. How long will it take to fill the empty pool if the drain is left open?

Question 15929: An empty swimming pool can be filled in 5hrs. When full, the pool can be drained in 17hrs. How long will it take to fill the empty pool if the drain is left open?
Answer by AnlytcPhil(1806) (Show Source): You can put this solution on YOUR website!
An empty swimming pool can be filled in 5hrs. When full, the pool can be drained in 17hrs. How long will it take to fill the empty pool if the drain is left open?
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Suppose it will take x hours.
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>>...An empty swimming pool can be filled in 5hrs...<<
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Translation:
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In 5 hours, 1 poolful of water goes in.
In 1 hour, 1/5 of a poolful of water goes in.
In x hours, x/5 of a poolful of water goes in.
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>>...the pool can be drained in 17hrs...<<
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Translation:
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In 17 hours, 1 poolful of water goes out.
In 1 hour, 1/17 of a poolful of water goes out.
In x hours, x/17 of a poolful of water goes out.
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In x hours:
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water coming in in x hours - water going out in x hours = 1 poolful
x/5 of a poolful - x/17 or a poolful = 1 poolful
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x/5 - x/17 = 1
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Can you solve that? If not post again. Answer 85/12 hours
or 7 1/12 hours or 7 hours 5 minutes.
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Edwin

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