## Combinations -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 – probability formulas

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…

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## Distributions – probability formulas

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…

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## Variance – probability formulas

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…

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## Expectation-probability formulas

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…