How do you do probability in math?

The Probability of Success = Number of successful outcomes/Number of outcomes.

E.g. Find the probability of choosing a red five or a black odd numbered card in a standard deck of 52 playing cards.

There are 2 red fives and 10 odd numbered cards, and a total of 52 cards, so:

=2/52+10/52

=12/52

3/13

Probability of Red 5 or a Black Odd = 3/13

* * * * *

The above is true only for discrete distributions, not for continuous variables. For a continuous variable, with probability distribution function p(x), the probability that x lies between two values, a and b (ie a