Three tanks of $2$ m$3$ capacity are each arranged so that when water is fed into the first an equal quantity of solution overflows from the first to the second tank, likewise from the second to third, and from the third to some point out of the system. Agitators keep the contents of each tank uniform in concentration. To start, let each of the tanks be full of the solution of concentration $0\mathrm{.}3$ kg$/$m$3.$ Run water into the first tank at $0\mathrm{.}1$ m$3/$min and let the overflows function as described above. Calculate the concentrations in the three tanks at the end of $15$ minutes using Euler's method.

Take At$=5$ min.