Question

What are the $4$ Laws of Probability?

Answer 1

Define probability.

Probability deals with the occurrence of a random event. The four basic rules of probability are :

1. Addition rule of probability : $\mathrm{P}(\mathrm{A}\mathrm{or}\mathrm{B})=\mathrm{P}\left(\mathrm{A}\right)+\mathrm{P}\left(\mathrm{B}\right)-\mathrm{P}(\mathrm{A}\mathrm{and}\mathrm{B})$
2. Multiplication rule of probability : $\mathrm{P}(\mathrm{A}\mathrm{and}\mathrm{B})=\mathrm{P}\left(\mathrm{A}\right)\times \mathrm{P}\left(\frac{\mathrm{B}}{\mathrm{A}}\right)$ or $\mathrm{P}\left(\mathrm{B}\right)\times \mathrm{P}\left(\frac{\mathrm{A}}{\mathrm{B}}\right)$
3. Complement rule of probability : $\mathrm{P}(\mathrm{not}\mathrm{A})=1-\mathrm{P}\left(\mathrm{A}\right)$
4. Total probability rule : The sum of the probabilities of all possible outcomes is $1$.