Mean

In statistics, the arithmetic mean is the sum of all the data values divided by the number of data values in the population. Its formula is given by:

$$\bar{x}=\frac{\Sigma f_i{x}_i}{n}$$

If we’re dealing with the whole population of data, we also represent the mean with $\mu$.

When discussing probability distributions, we refer to the mean as the expected value.

$$E(X)=\Sigma (x\times P(X=x))$$