Operations Research20815 marksNumerical: PERT expected time variancePERT network diagrams
Project Completion Time and Variance Analysis A project consists of nine activities whose time estimates (in weeks) and other characteristics are given below. What is the expected project completion time and its variance? | Activities | A | B | C | D | E | F | G | H | I | |---|---|---|---|---|---|--
Project Completion Time and Variance Analysis
A project consists of nine activities whose time estimates (in weeks) and other characteristics are given below. What is the expected project completion time and its variance?
| Activities | A | B | C | D | E | F | G | H | I |
|---|---|---|---|---|---|---|---|---|---|
| Preceding activities | - | - | - | A | A | B,D | B,D | C,F | E |
| Optimistic time | 2 | 6 | 6 | 2 | 11 | 8 | 3 | 9 | 4 |
| Most likely time | 4 | 6 | 12 | 5 | 14 | 10 | 6 | 15 | 10 |
| Pessimistic time | 6 | 6 | 24 | 8 | 23 | 12 | 9 | 27 | 16 |
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Activity Predecessors $to$ $tm$ $tp$ -------------------------------------------- A - 2 4 6 B - 6 6 6 C - 6 12 24 D A 2 5 8 E A 11 14 23 F B, D 8 10 12 G B, D 3 6 9 H C, F 9 15 27 I E 4 10 16 $$te = \frac{to + 4tm + tp}{6}, \qquad \sigma^2 = \left(\frac{tp - to}{6}\right)^2$$ Activity $te$