http://www.alsenosy.com | http://www.professionalengineers.us(tO+tM+tP)/ 3 .Triangulardistributionisusedwhenthereareinsufficienthistoricaldataorwhen
using judgmentaldata. Durationestimates basedon three pointswith an assumeddistribution
provideanexpecteddurationandclarifytherangeofuncertaintyaroundtheexpectedduration.
94 .Answer:A.
PMBOK® Guide, page 201 , Section 6. 4. 2. 4
Three Point Estimating
...
The accuracy of single-point duration estimates may be improved by considering estimation
uncertaintyandrisk.Usingthree-pointestimateshelpsdefineanapproximaterangeforanactivity's
duration:
o Mostlikely(tM).Thisestimateisbasedonthedurationoftheactivity,giventheresourceslikelyto
beassigned,theirproductivity,realisticexpectationsofavailabilityfortheactivity,dependencieson
otherparticipants,andinterruptions.
o Optimistic(tO).Theactivitydurationbasedonanalysisofthebest-casescenariofortheactivity.
o Pessimistic (tP). The duration based on analysis of the worst-case scenario for the activity.
Dependingontheassumeddistributionofvalueswithintherangeofthethreeestimates,the
expectedduration,tE,canbecalculated.Onecommonlyusedformulaistriangulardistribution:tE
= (tO+tM+tP)/ 3 .Triangulardistributionisusedwhenthereareinsufficienthistoricaldataor
when using judgmental data. Duration estimates based on three points with an assumed
distribution provide an expected duration and clarify the range of uncertainty around the
expectedduration.
95 .Answer:A.
PMBOK® Guide, pages 210 – 211 , Section 6. 5. 2. 2
Critical Path Method
Thecriticalpathmethod,whichisamethodusedtoestimatetheminimumprojectdurationand
determinethe amountofscheduling flexibilityon thelogicalnetworkpathswithinthe schedule
model.Thisschedulenetworkanalysistechniquecalculatestheearlystart,earlyfinish,latestart,and
latefinishdatesforallactivitieswithoutregardforanyresourcelimitationsbyperformingaforward
and backward pass analysisthrough theschedule network,as shownin Figure 6 – 18. In this
example,thelongestpathincludesactivitiesA,C,andD,andtherefore,thesequenceofA–C–Dis
thecritical path.Thecritical pathis thesequence ofactivitiesthatrepresentsthe longestpath
throughaproject,whichdeterminestheshortestpossibleprojectduration.
Onanynetworkpath,thescheduleflexibilityismeasuredbytheamountoftimethataschedule
activitycanbedelayedorextendedfromitsearlystartdatewithoutdelayingtheprojectfinishdate
or violating a schedule constraint, and is termed total float. A CPM critical path is normally
characterizedbyzerototalfloatonthecriticalpath.AsimplementedwithPDMsequencing,critical
pathsmayhavepositive,zero,ornegativetotalfloatdependingonconstraintsappliedAnyactivityon
thecriticalpathiscalledacriticalpathactivity.Positivetotalfloatiscausedwhenthebackward pass
is calculated from a schedule constraintthat is later than the early finish date thathas been
calculatedduringforwardpasscalculation.Negativetotalfloatiscausedwhenaconstraintonthe
latedatesisviolatedbydurationandlogic.Schedulenetworksmayhavemultiplenear-criticalpaths.
Manysoftwarepackagesallowtheusertodefinetheparametersusedtodeterminethecritical