# Expectation (math)

### From Conservapedia

The mathematical **expectation** of a continuously distributed random variable *X* with probability density function
*f*(*x*) is

The expectation is also known as the mean of *X*.

The expectation with respect to some function *g*(*X*) where *X* is distributed according to *f*(*x*) is

For a discretely distributed random variable *X* with probability mass function
*p*_{k} it is

E[ *X*] =∑ *p*_{k}*x*_{k}.*k*