Answer
The theoretical probability of event $ E,\ \text{}\ \text{denoted}\ \text{by}$ $ P\left( E \right)$, is the $\text{number}\ \text{of}\ \text{outcomes}\ \text{in}\ \text{event}\ E $ divided by the total number of possible outcomes.
Work Step by Step
We know that if an event $ E $ has $ n\left( E \right)$ equally likely outcomes and its sample space $ S $ has $ n\left( S \right)$ equally likely outcomes, theoretical probability of event $ E $ is denoted by $ P\left( E \right)$ as given below;
$ P\left( E \right)=\frac{\text{number}\ \text{of}\ \text{outcomes}\,\text{in}\ \text{event}\,E}{\text{number}\ \text{of}\text{outcomes}\ \text{in}\ \text{sample}\ \text{space}\ S}$
