I'm interested in a few things here. Firstly, do you use mathhammer, and if so, how much and for what purpose? as well as gauging if people would like to learn more about how to both do simple and more complex probability, and how to use and apply probability to a game.
If people are interested I will happily write up a small passage on probability (basic and binomial if your interested), but I won't bother if no will read it (simplifying binomial is a bit of an effort, though I'm happy to do it).
I personally use it allot when list building, both to work out how useful certain weapons are as well as what sort of impact a unit will have on other units in assault and shooting. It can give a good idea of the damage output of a unit as well as what sort of punishment it can take. Also, basic probability can be used on the fly in a game to work out whether a certain shot or charge is going to be worth it.