\begin{definition}[Definition:Relative Frequency Model]
The '''relative frequency model''' is a mathematical model that defines the probability of an event occurring as follows:
:$\map \Pr {\text {event occurring} } := \dfrac {\paren {\text {observed number of times event has occurred in the past} } } {\paren {\text {observed number of times event has occurred or not occurred} } }$
That is, the probability of an event happening is defined as the '''relative frequency''' of a finite number of events of a particular type in some finite reference class of events. 
Symbolically:
:$\map \Pr \omega := \dfrac {f_{\omega} } n$
where:
:$\omega$ is an elementary event
:$f_{\omega}$ is how many times $\omega$ occurred
:$n$ is the number of trials observed.
\end{definition}