Maybe there already is solution for that and if it is so, then maybe someone can tell me where I can find it.
I have 2 boxes. In first box there are 3 white and 2 black balls. In second box there are 4 black and 4 white balls. Then I randomly pick one ball from first box and put it in second box. What is the probability that I pick white ball from the second box?
I think that I need to calculate combinations for black balls and then for white balls (for second box after I put in random ball from first box) and then multiply them.