I'm dealing with a problem in probability, there's:
Let P be an probability function in $\Omega{\{a1, a2, a3\}}$, find $P(a1)$ whether:
$P(a2) = \dfrac{1}{3}$ and $P(a3) = \dfrac{1}{4}$
I don't even know from where to start, since I'm a beginner in probability;
Thanks in advance;