\qquad \begin{tabular}{cccc} \multicolumn{1}{c|}{$x_i$} & c($x_i$) & P($x_i$) & $c(x_i)\cdot$P($x_i$) \\ \hline \multicolumn{1}{c|}{$x_1$} & 2 & 0.1 & 0.2 \\ \multicolumn{1}{c|}{$x_2$} & 1 & 0.3 & 0.3 \\ \multicolumn{1}{c|}{$x_3$} & 5 & 0.2 & 1.0 \\ \hline \multicolumn{4}{c}{$c(X)=0.2+0.3+1.0=1.5$} \end{tabular}