SOLUTION: I am totally lost as where to start or set this up. Could you please help me? A water tank has an inlet pipe and a drain pipe. A full tank can be emptied in 30 minutes if the dr

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: I am totally lost as where to start or set this up. Could you please help me? A water tank has an inlet pipe and a drain pipe. A full tank can be emptied in 30 minutes if the dr      Log On

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Question 179867This question is from textbook
: I am totally lost as where to start or set this up. Could you please help
me?
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 accidently opened when the tank is full, then how long will it take to empty the tank? Thanks, Judy This question is from textbook

Found 2 solutions by solver91311, Mathtut:
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


Emptying the tank takes 30 minutes. That means that the drain pipe can do of the job of emptying the tank in one minute.

Similarly, the fill pipe can do of the job of emptying the tank in one minute.

Working against one another, the tank will empty at a rate of of the tank per minute. (We know it is emptying because is larger than )



So if of the tank empties in one minute, it takes 90 minutes to empty the whole tank.

John

Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
it can drain 1/30 of the tank per minute
it can fill 1/45 of the tank per minute
:
together -1/30+1/45=-3/90+2/90=-1/90
:
so it draining at a rate of 1/90 of the tank per minute
:
therefore it will take 90 minutes to empty the tank under the given scenario