The estimated times and immediate predecessors for the activities in a project at Howard Umrah’s retinal scanning company are given in the following table. Assume that the activity times are independent. Time (weeks) Immediate Time (weeks) Immediate b Predecessor(s Activity a Activity a Predecessors 9 10 13 9 12 This exercise contains only parts a b, c, d, and e a) Based on the activity time estimates. the expected times and variance for each of the activities are (round your response to two decimal places Expected Activity Variance Time b) The expected completion time of the critical path weeks (round your response to two decimal places The expected completion time of the path other than the critical path weeks (round your response to two decimal places)

## Expert Answer

the expected time for each activity is as follows, it can be calculated by the formula= To+4Tm+Tp/ 6, where To is the optimistic time, Tm is the most likely time and Tp is the pessimist time.

A= 9+4*10+13)/6= 62/6= 10.33

B= 6+4*11+17)/6= 67/6= 11.1

C= 8+ 4*10+13)/6= 61/6= 10.1

D= 4+4*9+12)= 52/6= 8.66

variance of each activity can be calculated by= Tp-To)/6=

A= 13-9)/6= 4/6=0.66

B= 17-6/6=11/6= 1.833

C= 13-8)/6= 5/6= 0.833

D= 12-4)/6=8/6= 1.33

the critical path may be=

the critical path is A-C, with durations of 10.33+10.1= 20.4

the variance on critical path activities are= 0.66+0.833= 1.493