A standard deck is composed of 52 cards, and contains 13 cards per suit. So, the theoretical probability of picking a card of any suit (and thus, in particular, a heart) is given by
[tex]P(\text{hearts}) = \dfrac{\text{\# of hearts in the deck}}{\text{\# of cards in the deck}} = \dfrac{13}{52} = \dfrac{1}{4}[/tex]
On the other hand, the experimental probability is (as the name suggests) the probability that we can deduce from our experiment: we picked 60 cards, and 12 of these were hearts. This means that it would seem to us that
[tex]P(\text{hearts}) = \dfrac{\text{\# of hearts we picked}}{\text{\# of cards we picked}} = \dfrac{12}{60} = \dfrac{1}{5}[/tex]
