Laws of Probability

Nothing new here, I’m just writing these down to remember them in the future

1. Two events both occurring cannot be more likely than each event occurring individually.
2. If two events are independent, the probability that they both occur is equal to the product of their individual probabilities.
3. If an event can have a number of different and distinct possible outcomes, A, B, C, and so on, then:
   • the probability that either A or B will occur is equal to the sum of the individual probabilities of A and B,
   • and the sum of the probabilities of all the possible outcomes (A, B, C, and so on) is 1 (that is, 100%).

I learned these from The Drunkards Walk, but they are also discussed here https://jonathanbecher.com/2017/06/25/the-3-laws-of-probability-everyone-should-know/