## Info

project duration. Now calculate LS using LS = LF-Duration, as shown in Table 3-23.

We will now move up one to task F. Is there any task that has an F in the predecessor? Yes, there is one—task G. Therefore make LF for task F = LS for task G and calculate task F LS as shown in Table 3-24 as well as the slack.

Task E, D, C, and B are the same way. Task E, D, and C each are contained in the predecessor column for task F. Therefore each one's LF is equal to the LS of task F as shown in Table 3-25. Task B is contained only in task D's predecessor; therefore, task B LF = the LS for task D.

Task A is contained in two tasks predecessors—tasks C and D. Therefore, we must take the minimum of the two LS's. Because task C is 5 and task D is 6, we take the 5 as shown in Table 3-26.

We now have enough information about the project to begin scheduling the work to be done, as shown in Table 3-27.

### PERT analysis

Now let's add uncertainty to the equation. We will use the beta distribution we have been using with budgeting. The difference is that we are using it to model time instead of dollars. Assume that the durations we have been using are the "most likely" numbers for the beta distribution. We generate the optimistic and pessimistic forecast of task times. These are shown in Table 3-28

TABLE 3-24 Eighth Cut Analysis