$4\mathrm{.}3$ The activities and time estimates for Xtrabyte project are listed in the table below.

$\backslash$table$[[$Activity$,$Description,Immediate Predecessors,Duration in weeks$],[$H$,$Basic design,$-,10],[$I$,$Hardware design for A$,$H$,8],[$J$,$Hardware design for B$,$H$,6],[$L$,$Software specifications,J$,2],[$N$,$Parts purchase for A$,$I,$4],[$Q$,$Software purchases,L$,5],[$S$,$Delivery of parts for B$,$N$,3],[$T$,$Software delivery,Q$,3],[$U$,$Assembly of A$,$S$,1],[$W$,$Test A$,$U$,2],[$Y$,$Final installation,W$,8],[$Z$,$Final system test,Y$,$T$,6]]$

$4\mathrm{.}3\mathrm{.}1$ Use the information in table above and construct the project network diagram $($AON$)$ for the Xtrabyte project. Show the ES$,$ LS$,$ EF and LF of each activity on the network.

$4\mathrm{.}3\mathrm{.}2$ Calculate and show the critical path of Xtrabyte project.