The three time estimates $t_o,t_m$ and $t_p$ of each activities of a project are given below:

$\backslash$table$[[$Activity$,t_o($days$),t_m($days$),t_p($days$)],[1-2,2,7,12],[1-3,7,12,19],[2-4,3,12,21],[3-4,1,8,9],[4-5,6,15,30],[3-5,2,5,8]]$

Draw the network diagram and find the expected duration and variance of each activity.