Mixing Different Solutions with Different Wavelengths to Get Different Colors?
You have to distinguish two sorts of colour mixing:


Subtractive mixing is observed when you mix two coloured solutions ot put two colored films on top of each other and shine white light through it. Here, $\mathrm{\color{yellow}{yellow}}$ and $\mathrm{\color{blue}{blue}}$ yield $\mathrm{\color{green}{green}}$.
Additive mixing is observed when you overlay two coloured light sources. In the RGB model, $\mathrm{\color{red}{red}}$ and $\mathrm{\color{green}{green}}$ yield $\mathrm{\color{yellow}{yellow}}$, the combination of $\mathrm{\color{red}{red}}$, $\mathrm{\color{green}{green}}$ and $\mathrm{\color{blue}{blue}}$ yields white.


As far as the wavelengths are concerned: Each "colour" is represented by a wavelength range, rather than an exact value. The fact that there's more than one red or green is intuitively understood - particularly by women ;)