A jar has $N$ marbles out of which $K$ are blue.

Randomly draw $n$ marbles from the jar, how likely $k$ of them are blue?

$$
p(k) = \frac{{K \choose k}{N-K \choose n-k}}{{N \choose n}}
\\[16pt]
\text{where $N$ is the population size,}\\
\text{$K$ is the number of success states in the population, }\\
\text{and $n$ is the number of draws.}
$$