Let's spend a few minutes talking about the basic concepts of probability. If you are already familiar with these concepts, you may want to skip this section. Otherwise, it will be interesting to deepen the basic knowledge needed to understand how probabilistic classification algorithms work.

In a bag, there are seven white balls and three black balls. Except for their color, the balls are identical; they are made of the same material, they are the same size, they are perfectly spherical, and so on. I'll put a hand in the bag without looking inside, pulling out a random ball. What is the probability that the pulled out ball is black?

- The balls in all are
*7 + 3 = 10*. By pulling out a ball, I have*10*possible ...