What is the probability of drawing an ace from a pack of 52 cards?

In a standard deck of cards:
* Total number of cards, $n(S)=52$
* Total number of aces, $n(E)=4$

The probability $P(E)$ of drawing an ace is given by:

$$P(E)=\frac{n(E)}{n(S)}=\frac{4}{52}=\frac{1}{13}$$