The activity details and their predecessors are given below use the PERT method to calculate the expected time $(1$ Mark$)$ and construct the network diagram $(1$ Mark$)$ to find the critical path of the activity $(1$ Mark$)$ also indicate the project duration $(1$ Mark$)$ with the standard deviation $(1$ Mark$).$

$\backslash$table$[[$Activity$,\backslash$table$[[$Predecessors the expected$],[$time$]],\backslash$table$[[$Optimistic$],[$time$],[($to$)]],\backslash$table$[[$Most likely$],[$time$],[(tm)$