Define "Critical path", "Slack time", "Resource Levelling" and "Dummy activity" with reference to PERT and CPM$.$

An architect has been awarded a contract to prepare plans for an urban renewal project. The job consists of the following activities and their estimated value. Draw a critical path arrow diagram for this project, indicate the critical path and calculate the total slack and free slack for each activity.

$\backslash$table$[[$Job$,$Description,Predecessor,$\backslash$table$[[$Expected time in$],[$days$]]],[$A$,\backslash$table$[[$Prepare preliminary$],[$sketches$]],$NA$,2],[$B$,$Outline specifications,NA$,1],[$C$,$Prepare drawings,A$,3],[$D$,$Write specifications,A B$,2],[$E$,$Run prints,C D$,1],[$F$,$Have specifications printed,B D$,3],[$G$,$Assemble bid package,E F$,1]]$