SOLUTION: With water from one hose, a swimming pool can be filled in 7 hours. A second, larger hose used alone can fill the pool in 4 hours. How long would it take to fill the pool if both h
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-> SOLUTION: With water from one hose, a swimming pool can be filled in 7 hours. A second, larger hose used alone can fill the pool in 4 hours. How long would it take to fill the pool if both h
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Question 499218: With water from one hose, a swimming pool can be filled in 7 hours. A second, larger hose used alone can fill the pool in 4 hours. How long would it take to fill the pool if both hoses were used simultaneously? Found 2 solutions by Earlsdon, oberobic:Answer by Earlsdon(6294) (Show Source):
You can put this solution on YOUR website! When the pool is full, we can say that 100% of the work has been done.
100% is simply 1.
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One hose can fill the pool in 7 hours, so it does 1/7 of the job per hr.
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The second host can fill the pool in 4 hr, so it does 1/4 of the job per hr.
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How many hours does it take to fill the pool?
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x = the hrs to fill the pool
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(1/7 + 1/4)*x = 1
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That says when we add the work done by the two hoses working together, and multiply by the time, we end up with 1 full pool.
1/7 + 1/4 = 4/28 + 7/28 = 11/28
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11/28*x = 1
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Multiply both sides by 28/11.
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x = 28/11 hr
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x = 2 6/11 hr
That works out to about 2 hr 33 minutes.
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Checking the answer:
1/7*28/11 = 28/77 = 4/11
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1/4*28/11 = 28/44 = 7/11
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4/11 + 7/11 = 11/11 = 1
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Answer:
It will take 28/11 = 2 6/11 hours to fill the pool.
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Done.
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