This document discusses different types of probability and theorems related to probability calculations. It defines probability, theoretical probability, experimental probability, and subjective probability. It then explains the theorem of total probability, which calculates the total probability of an event by considering mutually exclusive events related to that event. Next, it introduces Bayes' theorem, which provides a mathematical rule for revising estimates based on new information or observations. Finally, it defines the theorem of compound probability, which is the probability of two events occurring simultaneously, and provides formulas for calculating compound probability for independent and dependent events.