The laws of probability govern the rules and principles that describe how probabilities behave in different situations. These laws provide a formal framework for reasoning about uncertainty and are fundamental to probability theory.
Here are some key laws of probability:
- Addition theorems (or additive law) of probability
- Multiplication theorem (or multiplicative law) of probability
Additive law of Probability:
The Additive Law of Probability, also known as the Addition Rule, describes how to calculate the probability of the union of two or more events.
There are two versions of the Additive Law:
- for mutually exclusive events
- for not mutually exclusive events.
→ Addition theorem of probability for mutually exclusive events

→ Addition theorem of probability for not mutually exclusive events

Multiplicative law of Probability:
The Multiplicative Law of Probability is a fundamental principle in probability theory that deals with the probability of the intersection of events.
There are two main versions of the Multiplicative Law:
- for independent events
- for dependent events
→ When events are Independent:


→ When events are dependent: