SOLUTION: A tank can be filled by a hose in 15 hours. It can be emptied by a drainpipe in 25 hours. If the drainpipe is open while the tank is being filled, how long does it take to fill the

Question 513152: A tank can be filled by a hose in 15 hours. It can be emptied by a drainpipe in 25 hours. If the drainpipe is open while the tank is being filled, how long does it take to fill the tank?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A tank can be filled by a hose in 15 hours. It can be emptied by a drainpipe in 25 hours. If the drainpipe is open while the tank is being filled, how long does it take to fill the tank?
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Fill rate: 1/15 job/hr
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Drain rate: 1/25 job/hr
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Together rate: 1/x job/hr
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Equation:
rate - rate = rate
1/15 - 1/25 = 1/x
---
Multiply thru by 75x to get:
5x - 3x = 75
2x = 75
x = 37.5 hrs (time to fill the tank together)
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Cheers,
stan H.
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