# Thread: Tank drained from a tank problem.

1. ## Tank drained from a tank problem.

I'm not sure how to start this problem. Can someone help me with this.

A large tank with capacity of 600L initially contains 200L of pure water. Brine with a salt concentration of 4g/L is pumped into the tank at a constant rate of 15L/min. The solution in the tank is well mixed at all times, and is drained from the tank at a rate of 10L/min. How much salt is in the tank at the moment the amount of brine in the tank reaches capacity?

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2. ## Re: Tank drained from a tank problem.

Hey JC05.

The first thing I would do is to try and represent the derivatives to the quantities. Once you get this you can get a set of equations to solve.

Start with defining all the variables and the derivatives of everything with respect to each other (including time).

By doing this you will understand how to do general problems of this kind (independently) in the future and it will make sense intuitively.