Table J.15
Consider the following problem in which four jobs that arrived this morning are to be processed on two machines. They start with the cutting machine and then go to the painting machine. The following processing times are available (in hours):

-Use the information in Table J.15. If the SPT rule is used to determine the sequence at the cutting machine and the same sequence is also used at the painting machine, what is the makespan through both machines?
A) fewer than or equal to 32 hours
B) greater than 32 hours but fewer than or equal to 34 hours
C) greater than 34 hours but fewer than or equal to 36 hours
D) greater than 36 hours

Question

Table J.15
Consider the following problem in which four jobs that arrived this morning are to be processed on two machines. They start with the cutting machine and then go to the painting machine. The following processing times are available (in hours):
 
-Use the information in Table J.15. If the SPT rule is used to determine the sequence at the cutting machine and the same sequence is also used at the painting machine, what is the makespan through both machines?
A) fewer than or equal to 32 hours 
B) greater than 32 hours but fewer than or equal to 34 hours 
C) greater than 34 hours but fewer than or equal to 36 hours 
D) greater than 36 hours

Quizplus · Accepted Answer

The SPT rule states that the shortest processing time should be scheduled first. Using this rule, the job sequence at the cutting machine would be: Job 2, Job 4, Job 1, Job 3. 
The processing times for each job would be:
- Cutting Machine: 
    - Job 2: 2 hours 
    - Job 4: 3 hours 
    - Job 1: 4 hours 
    - Job 3: 6 hours 
- Painting Machine: 
    - Job 2: 5 hours 
    - Job 4: 4 hours 
    - Job 1: 3 hours 
    - Job 3: 2 hours 
The makespan is the total time needed to process all the jobs. In this case, the makespan would be 36 hours (2+3+4+6 for cutting + 5+4+3+2 for painting). Therefore, the answer is C.

Table J.15 Consider the Following Problem in Which Four Jobs That Arrived