Calculate expected time or duration for each activity

Question

Project path A-C-E-J has these activity time estimates in days:

Activity                 Optimistic                   Most Likely                Pessimistic

     A                             3                                  4                                   5

     C                             9                                12                                 14

     E                           12                                15                                 20

     J                              7                                  9                                   9

Compute the expected time or duration for each activity, the variance for each activity, and the expected duration and variance for the path.