chedulin (1) Use priority scheduling rules (SPT, EDD, and LS) and Johnson\'s rul
ID: 360027 • Letter: C
Question
chedulin (1) Use priority scheduling rules (SPT, EDD, and LS) and Johnson's rule to determine the sequences for scheduling the seven jobs listed below. All jobs must follow the same sequence of machine first, and then polish. Draw Gantt charts showing the scheduling of these jobs. Determine the make-span (throughput time), average time per job, machine utilization, number of jobs late, average lateness, and maximum lateness of each sequence Time Required for Job, hours Work Center 10 Machine Polish 12 20 17 25 19 Due Time, hours 15Explanation / Answer
Determine total processing time for each job as follows:
Job
Machine
Polish
Due date
Total Processing Time
A
10
2
15
10+2 = 12
B
6
3
20
9
C
5
12
18
17
D
4
5
17
9
E
6
9
22
15
F
9
11
25
20
G
7
6
19
13
A) According to shortest processing time (SPT) rule, sequence job from shortest production time required job first and so on,
Sequence
1
2
3
4
5
6
7
Job
D
B
A
G
E
C
F
Processing time
9
9
12
13
15
17
20
Scheduling according to SPT:
Job
Machine
Polish
Machine 1 Start
Machine 1 Finish
Machine 2 Start
Machine 2 Finish
Machine 2 Idle
Due Date
Lateness
D
4
5
0
4
4
9
4
17
0
B
6
3
4
10
10
13
1
20
0
A
10
2
10
20
20
22
7
15
7
G
7
6
20
27
27
33
5
19
14
E
6
9
27
33
33
42
0
22
20
C
5
12
33
38
42
54
0
18
36
F
9
11
38
47
54
65
0
25
40
Total
17
117
Make-span = 65 hours
Average time per job = make-span/number of jobs = 9.29 hours
Number of jobs late = 5
Maximum lateness = 40 hours
Average lateness = total lateness/# of jobs late = 117/5 = 23.4 hours
b) According to Early Due Date (EDD) rule, sequence job first with earliest Due date and so no
Sequence
1
2
3
4
5
6
7
Job
A
D
C
G
B
E
F
Due Date
15
17
18
19
20
22
25
Job
Time on Machine 1
Time on Machine 2
Machine 1 Start
Machine 1 Finish
Machine 2 Start
Machine 2 Finish
Machine 2 Idle
Due Date
Lateness
A
10
2
0
10
10
12
10
15
0
D
4
5
10
14
14
19
2
17
2
C
5
12
14
19
19
31
0
18
13
G
7
6
19
26
31
37
0
19
18
B
6
3
26
32
37
40
0
20
20
E
6
9
32
38
40
49
0
22
27
F
9
11
38
47
49
60
0
25
35
Total
12
115
Make-span = 60 hours
Average time per job = make-span/number of jobs = 60/7 = 8.57 hours
Number of jobs late = 6
Maximum lateness = 35 hours
Average lateness = total lateness/# of jobs late = 115/6 = 19.17 hours
c.
According to Johnson Rule, sequence the job first on machine 1 if the processing time is minimum on machine 1 otherwise on sequence last on machine 2. Repeat same for all the jobs.
Sequence
1
2
3
4
5
6
7
Job
D
C
E
F
G
B
A
Minimum time on Machine
1
1
1
2
2
2
Job
Time on Machine 1
Time on Machine 2
Machine 1 Start
Machine 1 Finish
Machine 2 Start
Machine 2 Finish
Machine 2 Idle
Due Date
Lateness
D
4
5
0
4
4
9
4
17
0
C
5
12
4
9
9
21
0
18
3
E
6
9
9
15
21
30
0
22
8
F
9
11
15
24
30
41
0
25
16
G
7
6
24
31
41
47
0
19
28
B
6
3
31
37
47
50
0
20
30
A
10
2
37
47
50
52
0
15
37
Total
4
122
Make-span = 52 hours
Average time per job = make-span/number of jobs = 52/7 = 7.4 hours
Number of jobs late = 6
Maximum lateness = 37 hours
Average lateness = total lateness/# of jobs late = 122/6 = 20.33 hours
Job
Machine
Polish
Due date
Total Processing Time
A
10
2
15
10+2 = 12
B
6
3
20
9
C
5
12
18
17
D
4
5
17
9
E
6
9
22
15
F
9
11
25
20
G
7
6
19
13
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