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I'm having trouble with a variant of the classic watertank equation. The data is as follows.

A tank contains 300 liters of saline water, containing a total of 1800 grams of salt. Through an inlet, saline water containing 5 grams/liter is pumped in at a speed of 2 liters/minute. The well-mixed solution is pumped out at a speed of 3 liters/minute. Compute the quantity of salt, in grams, after 100 minutes.

Here's my attempt at solving this:

[tex]

V(t)=300-t

[/tex]

[tex]

\frac{dS}{dt}=10t-3\frac{S}{V}

[/tex]

[tex]

S(0)=1800

[/tex]

Running it in the ODE Analyzer in MAPLE got me [tex]S(100)\approx33867[/tex], which isn't the solution. Can anyone spot what I've done wrong?

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# Classic watertank equation

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