probability formulas

Combinations An arrangement of objects in which the order is not important is called a combination. This is different from permutation where the order matters. For example, suppose we are…

Permutations A permutation is an arrangement, or listing, of objects in which the order is important. In previous lessons, we looked at examples of the number of permutations of n…

Distributions Normal distribution: The normal distribution (also called Gaussian distribution) is the most used statistical distribution because of the many physical, biological, and social processes that it can model. The…

Variance In probability and statistics, the variance of a random variable is the average value of the square distance from the mean value. It represents the how the random variable…

Expectation In probability and statistics, the expectation or expected value, is the weighted average value of a random variable. Expectation of continuous random variable: $$ E(X)= \int\limits_{-\infty}^{\infty} x P(x) dx…

Basics of probability A probability is a number that reflects the chance or likelihood that a particular event will occur. Probabilities can be expressed as proportions that range from 0…