$13.$ Use the network diagram and the table to answer de table to answer the following questions: Finish Start ACTIVITY OPTIMISTIC MOST LIKELY PESSIMISTIC EXPECTED TIME VARIANCE $2\mathrm{.}50\mathrm{.}25$ N$/$A N$/$A N$/$A $30\mathrm{.}5$ N$/$A N$/$A N$/$A $0\mathrm{.}7$ N$/$A N$/$A N$/$A $0\mathrm{.}6$ N$/$A N$/$A N$/$A $0\mathrm{.}6$ N$/$A N$/$A N$/$A $0\mathrm{.}4$ N$/$A N$/$A N$/$A $0\mathrm{.}82$ a$.$ Fill the empty cells in the diagram and table. b$.$ What is the critical path? c$.$ What is the expected project completion time? d$.$ What is the variance of project completion time? e$.$ What is the probability that this project can be completed in $16$ or fewer days? f$.$ What is the probability that this project would be completed in more than $19$ days?