Filling a tank

[kelly1]

Another word problem! Any help is greatly appreciated.

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 opened when the tank is full, then how long will it take to empty the tank? Thanks!!

 

[stapel]

Convert the times to rates. For instance, if something takes full effect in thirty minutes, then how much effect does that process have in one minute? Combine the rates, and set equal to the total desired process.

If you get stuck, please reply showing all of the steps and reasoning you have tried thus far.

Thank you.

Eliz.