Consider the Network Described in the Table Below A Calculate the Expected Duration of Each Activity

Consider the network described in the table below.
$\begin{array} { | c | c | c | c | c | } \hline \text { Activity } & \begin{array} { c } \text { Immediate } \\\text { Predecessor(s) }\end{array} & \text { Pessimistic } & \text { Probable } & \text { Optimistic } \\\hline \mathrm{J} & -- & 15 & 10 & 8 \\\hline \mathrm{K} & -- & 9 & 8 & 7 \\\hline \mathrm{L} & \mathrm{J} & 10 & 6 & 5 \\\hline \mathrm{M} & \mathrm{J} & 3 & 3 & 3 \\\hline \mathrm{N} & \mathrm{K}, \mathrm{M} & 9 & 5 & 1 \\\hline \mathrm{O} & \mathrm{K}, \mathrm{M} & 10 & 7 & 4 \\\hline \mathrm{P} & \mathrm{L}, \mathrm{N} & 10 & 8 & 3 \\\hline\end{array}$
a. Calculate the expected duration of each activity.
b. Calculate the expected duration and variance of the critical path.
c. Calculate the probability that the project will be completed in fewer than 30 time units.