Probability in the classical model is the ratio of favorable outcomes to all possible outcomes.
$$P(A)=\frac{k}{n}$$
where,
P(A)— probability of event A;
k— number of favorable outcomes;
n— number of possible outcomes.
Probability measures how likely an event is to happen.
It is the number of favorable outcomes divided by the number of possible outcomes.
The sample space is the set of all possible outcomes in an experiment.