$3\mathrm{.}6$ Given the activities whose sequence is described by the following table, draw the appropriate activity$-$on$-$arrow $($AOA$)$ network diagram.

a$.$ Which activities are on the critical path?

b$.$ What is the length of the critical path?

$\backslash$table$[[$ACTIVITY$,$IMMEDIATE,TIME $($DAYS$)],[$A$,-,5],[$B$,$A$,2],[$C$,$A$,4],[$D$,$B$,5],[$E$,$B$,5],[$F$,$C$,5],[$G$,$E$,$ F$,2]]$