Consider the network described in the table below.

$\backslash$table$[[$Immediate$],[$Activity$,\backslash$table$[[$Predecesso$],[$r$($s$)]],$Pessimistic,Probable,Optimistic$],[$J$,--,15,10,8],[$K$,--,9,8,7],[$L$,$J$,10,6,5],[$M$,$J$,3,3,3],[$N$,$K$,$M$,9,5,1],[$O$,$K$,$M$,10,7,4],[$P$,$L$,$N$,10,8,3]]$

a$.$ Calculate the expected duration of each activity.

b$.$ Calculate the expected duration and variance of the