$3.(30$ points$)$ Suppose the duration of the activities of the ad campaign are, in fact, uncertain: $\backslash$begin$\{$tabular$\}\{|$c$|$c$|$c$|$c$|$c$|\}\backslash$hline Activity & $\backslash$begin$\{$tabular$\}\{$c$\}$ Immediate $\backslash \backslash$ Predecessor $\backslash$end$\{$tabular$\}$ & $\backslash$begin$\{$tabular$\}\{$c$\}$ Optimistic $\backslash \backslash$ Likely $\backslash$end$\{$tabular$\}$ & $\backslash$begin$\{$tabular$\}\{$c$\}$ Pessimistic $\backslash \backslash$ Lim $\backslash$end$\{$tabular$\}\backslash \backslash \backslash$hline A & $-$ & $1$ & $2$ & $3\backslash \backslash \backslash$hline B & $-$ & $4$ & $6$ & $8\backslash \backslash \backslash$hline C & B & $3$ & $3$ & $3\backslash \backslash \backslash$hline D & A & $2$ & $8$ & $10\backslash \backslash \backslash$hline E & A$,$ C & $3$ & $6$ & $9\backslash \backslash \backslash$hline F & B & $1$ & $8$ & $15\backslash \backslash \backslash$hline G & E$,$ F & $4$ & $5$ & $6\backslash \backslash \backslash$hline H & D$,$ G & $0$ & $0$ & $0\backslash \backslash \backslash$hline $\backslash$end$\{$tabular$\}($a$)(15$ points$)$ Calculate the ES$,$ EF$,$ LS$,$ LF and Slack for each activity. $($b$)\backslash ((5\backslash )$ points$)$ Determine the critical path and critical activities. $($c$)(10$ points$)$ What is the probability that the project will finish in $20$ days?