QUESTION $2(10$ MARKS$)$

Mario Manufacturing Sdn$.$ Bhd$.$ develops a new pollution control device for treating waste water from steel industries. The development and installation of this device requires nine $(9)$ activities and their related time estimates and costs are given in Table $2.$

Table $2$: Activities, time estimates and costs for pollution control device installation

$\backslash$table$[[$Activity$,\backslash$table$[[$Immediate$],[$Predecessor$($s$)]],\backslash$table$[[$Normal time$],[($weeks$)]],\backslash$table$[[$Maximum Crash$],[$time $($weeks$)]],\backslash$table$[[$Crash cost$],[$per week$],[($RM$)]]],[$A$,-,9,1,1900],[$B$,$A$,7,3,2100],[$C$,$A$,3,1,2500],[$D$,$B$,6,3,2700],[$E$,$B$,8,1,1400],[$F$,$C$,4,2,5000],[$G$,$E$,$ F$,6,2,1600],[$H$,$D$,5,2,1000],[$I$,$H$,3,1,2300]]$

a$.$ Construct a network diagram based on Activity$-$on$-$Node $($AoN$)$ for the above development project. Determine the minimum project completion time and the critical path activities.

$(4$ marks$)$

b$.$ If the completion time of the project needs to be shortened by two $(2)$ weeks, determine which activities are involved to provide minimum additional cost. Show the final network diagram after these changes.

$(6$ marks$)$