Consider the project with the following estimates for activity times and precedence relationships:

$\backslash$table$[[$Activity$,\backslash$table$[[$Optimistic$],[$Time$]],\backslash$table$[[$Most$],[$Likely Time$]],\backslash$table$[[$Pessimistic$],[$Time$]],\backslash$table$[[$Immediate$],[$Predecessor$($s$)]]],[$A$,3,4,5,--],[$B$,5,7,9,--],[$C$,2,3,10,$A$],[$D$,2,5,8,$B$],[$E$,1,7,7,$B$],[$F$,3,5,7,$C$,$ D$],[$G$,7,8,9,$D$,$ E$],[$H$,2,6,10,$F$]]$

$($a$)$ What is the expected duration of the project?

$($b$)$ What is the project variance?

$($c$)$ If the deadline of the project is $25$ days, what is the probability of finishing the project on time?