Problem 6-6
| Twelve tasks, with times and precedence requirements as shown in the following table, are to be assigned to workstations that have a fixed machine cycle time of 1.5 minutes. Two heuristic rules will be tried: (1) greatest positional weight, and (2) greatest number of following tasks. |
| In each case, the tiebreaker will be shortest task time. |
| Task | Length (minutes) |
Immediate Predecessor |
| a | 0.1 | – |
| b | 0.2 | a |
| c | 0.9 | b |
| d | 0.6 | c |
| e | 0.1 | – |
| f | 0.2 | d, e |
| g | 0.4 | f |
| h | 0.1 | g |
| i | 0.2 | h |
| j | 0.7 | i |
| k | 0.3 | j |
| l | 0.2 | k |
|
|
||
| b. | Assign tasks to stations under each of the two rules. |
| (1) greatest positional weight (shortest task time as tiebreaker) |
| Work Station | Tasks |
| I | |
| II | |
| III | |
|
|
|
| (2) greatest number of following tasks (shortest task time as tiebreaker) |
| Work Station | Tasks |
| I | |
| II | |
| III | |
|
|
|
| c. | Compute the percentage of idle time for each rule. (Round your answer to 2 decimal places. Omit the “%” sign in your response.) |
| Percentage of idle time | [removed] % |
