We have six jobs, each of which must go through machine A, B & C in the order of ABC. Processing times (in hours) are given: - | Job | 1 | 2 | 3 | 4 | 5 | 6 | |-----------|---|---|---|---|----|---| | Machine A | 8 | 3 | 7 | 2 | 5 | 1 | | Machine B | 3 | 4 | 5 | 2 | 1 | 6 | | Machine C | 8 | 7 | 6 | 9 | 10 | 9 |

Determine minimum elapsed time, idle time for machines, and idle time for jobs. -

Using Johnson’s algorithm to determine sequence of jobs:

Sequence: 456213

Minimum elapsed time: 53 hours

Idle time for machines:

• For A: 53 – 26 = 27 hours
• For B: 2 + 7-4 + 19-18 + 26-22 + 53-31 = 32 hours
• For C: 4 hours

Idle time for jobs (time they spend waiting to get loaded on a machine, i.e. inprocess inventory):

$ - 1: 39-22 = 17 \ hours \hspace{3cm} - 4: 0 \ hours \\ - 2: 14-11 + 32-18 = 17 \ hours \hspace{1.3cm} - 5: 13-8 = 5 \ hours \\ - 3: 47-31 = 16 \ hours \hspace{3cm} - 6: 23-14 = 9 \ hour$