SOLUTION: 62. A water tank has an inlet pipe and a drain pipe. A full tank can be emptied in 30 minutes if the drain is opened and an empty tank can be filled in 45 minutes with the inlet p

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: 62. A water tank has an inlet pipe and a drain pipe. A full tank can be emptied in 30 minutes if the drain is opened and an empty tank can be filled in 45 minutes with the inlet p      Log On

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Question 66728: 62. A water tank has an inlet pipe and a drain pipe. A full tank can be emptied in 30 minutes if the drain is opened and an empty tank can be filled in 45 minutes with the inlet pipe opened. If both pipes are accidentially opened when the tank is full, then how long will it take to empty the tank?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A water tank has an inlet pipe and a drain pipe. A full tank can be emptied in 30 minutes if the drain is opened and an empty tank can be filled in 45 minutes with the inlet pipe opened. If both pipes are accidentially opened when the tank is full, then how long will it take to empty the tank?
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Outlet pipe DATa:
Time to empty: 30 min/job ; Rate= 1/30 job/min
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Inlet pipe DATA:
Time to fill: 45 min/job ; Rate = 1/45 job/min
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Together DATA:
Time to empty: x min/job : Rate = 1/x job/min
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EQUATION:
Fill rate - Empty rate = together rate
1/45 - 1/30 = 1/x
75/{30*45] =1/x
x=[30*45/75]
x=18 hrs (Time to empty if both pipes are open)
Cheers,
Stan H>