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Chapter 7Project ManagementPERT
Page 69CPM with three time estimatesThe three estimates of an activity time are:a ( to) =Optimistic time;theminimumreasonable period oftime in which anactivity can be completed.m (tm) =Most likely time;thebest guessof thetime required.b (tp) =Pessimistic time;themaximumreasonableperiod of time in which an activityCalculation of Expected Time (ET)64bmaET++=26-=abVariance
ProblemThe home office billing department of a chain ofdepartment stores prepares monthly inventory reports for use bythe stores purchasing agents.Given the following information,use PERT method to determine:a.How long the total process time will take?b.Which jobs can be delayed without delaying the earlystart of any subsequent activity?(slack)
JobABCDEFGHImmediatePredecessors-AAB, CB, CED, FGambTime(hours)00091011182022253035152025104550102030000ExpectedTime(ET)0102030204020064bmaET++=A,0B,10C,20D,30E,20F,40G,20H,0Net Work DiagramNo. 9/83