In probability theory, what is the variance of a discrete random variable $X$ with values $\{1,2,3\}$ and probabilities $P(X=1)=0.3$, $P(X=2)=0.5$, and $P(X=3)=0.2$?

Practise more Mathematics A: Functions, Calculus, Complex Numbers and Probability.

Free questions with an explanation for every one, and full timed Exames Nacionais Secundário (Portugal) mock tests.