An urn contains four white balls and six black. Three balls are drawn with replacement. Let $x$ be the number of white balls. Calcaulate $E (x)$, $VAR(x)$ and $\sigma x$.
I don't know how to calculate $E(x) =\sum\limits_{i=1}^{n} X_i P(X_i)$.
An urn contains four white balls and six black. Three balls are drawn with replacement. Let $x$ be the number of white balls. Calcaulate $E (x)$, $VAR(x)$ and $\sigma x$.
I don't know how to calculate $E(x) =\sum\limits_{i=1}^{n} X_i P(X_i)$.