In: Operations Management
Consider the following precedence chart:
| ACTIVITY | PRECEDING ACTIVITIES | OPTIMISTIC TIME (days) | MOST LIKELY TIME (days) | PESSIMISTIC TIME (days) |
| A | - | 5 | 10 | 15 |
| B | - | 10 | 12 | 14 |
| C | - | 10 | 10 | 10 |
| D | B,C | 2 | 4 | 6 |
| E | A | 4 | 8 | 12 |
| F | A | 4 | 8 | 12 |
| G | D,E | 10 | 12 | 14 |
| I | F | 4 | 8 | 12 |
| J | G | 2 | 4 | 6 |
The total slack for activity C is __________
| a. |
0 |
|
| b. |
2 |
|
| c. |
8 |
|
| d. |
4 |
The expected durations of each activity are presented below :
|
Task |
Optimistic (O) |
Most likely ( m) |
Pessimistic(P) |
Expected duration |
|
A |
5 |
10 |
15 |
10.00 |
|
B |
10 |
12 |
14 |
12.00 |
|
C |
10 |
10 |
10 |
10.00 |
|
D |
2 |
4 |
6 |
4.00 |
|
E |
4 |
8 |
12 |
8.00 |
|
F |
4 |
8 |
12 |
8.00 |
|
G |
10 |
12 |
14 |
12.00 |
|
I |
4 |
8 |
12 |
8.00 |
|
J |
2 |
4 |
6 |
4.00 |
Expected duration = ( Optimistic duration + 4 x Most likely duration + Pessimistic duration) / 6
The precedence diagram of activities as follows :
|
A |
B |
C |
|
|
F |
E |
D |
|
|
I |
G |
||
|
J |
|||
The possible parallel paths and their expected durations as follows :
A-F-I = 10 + 8 + 8 = 26
A-E-G-J = 10 + 8 + 12 + 4 = 34
B-D-G-J = 12 + 4 + 12 + 4 = 32
C-D-G-J = 10 + 4 + 12 + 4 = 30
Since A-E-G-J has the longest Expected duration, it forms the critical path.
Slack for activities C, D
= Duration A-E-G-J – Duration C-D-G-J
= 34 – 30 DAYS
= 4 days
|
TOTAL SLACK FOR ACTIVITY C = 4 DAYS |