The probability of occurence of any event is defined as the ratio of possible outcome to the total outcome.
The number of possible outcome for a diamond card from the deck is,
[tex]n(p)=13[/tex]The total possible outcome for the deck is,
[tex]n(t)=52[/tex]Determie the probability for the card to be diamond.
[tex]\begin{gathered} P=\frac{n(p)}{n(t)} \\ =\frac{13}{52} \\ =\frac{1}{4} \end{gathered}[/tex]So answer is 1/4.