PLEASE SHOW WORK SO I CAN FOLLOW ALONG--THANKS! The following table contains inf
ID: 451369 • Letter: P
Question
PLEASE SHOW WORK SO I CAN FOLLOW ALONG--THANKS!
The following table contains information regarding jobs that are to be scheduled through one machine:
OPERATIONS TIME
JOB
PROCESSING TIME(DAYS)
DUE DATE
A
4
20
B
12
30
C
2
15
D
11
16
E
10
18
F
3
5
G
6
9
1.) What is the shortest operating time (SOT) schedule (sequence)?
2.) What is the slack time remaining (STR) schedule (sequence)?
3.) For the schedule (sequence) F-G-C-D-E-A-B, compute mean flow time?
OPERATIONS TIME
JOB
PROCESSING TIME(DAYS)
DUE DATE
A
4
20
B
12
30
C
2
15
D
11
16
E
10
18
F
3
5
G
6
9
Explanation / Answer
Shortest operating time (SOT) schedule is the order of work where highest preference is given to the job with shortest operating time. Accordingly, mean flow time is calculated.
JOB
PROCESSING TIME(DAYS)
DUE DATE
Flow Time
C
2
15
0+2=2
F
3
5
2+3 = 5
A
4
20
5+4=9
G
6
9
9+6=15
E
10
18
15+10=25
D
11
16
25+11=36
B
12
30
36+12=48
Mean Flow time = (2+5+9+15+25+36+48)/7 = 20 days
2. (STR)
Slack time remaining = Due date time remaining – Processing time
JOB
PROCESSING TIME(DAYS)
DUE DATE
Slack
A
4
20
20-4=16
B
12
30
30-12=18
C
2
15
15-2 = 13
D
11
16
16-11=5
E
10
18
18-10 = 8
F
3
5
5-3 = 2
G
6
9
9-6 = 3
On the basis of slack time remaining , following sequence will be followed.
JOB
PROCESSING TIME(DAYS)
DUE DATE
Slack
F
3
5
2
G
6
9
3
D
11
16
5
E
10
18
8
C
2
15
13
A
4
20
16
B
12
30
18
3.
For the Job Sequence of F-G-C-D-E-A-B
JOB
PROCESSING TIME(DAYS)
DUE DATE
Flow Time
F
3
5
0+3 = 3
G
6
9
3+6 = 9
C
2
15
9+2 = 11
D
11
16
11+11=22
E
10
18
22+10=32
A
4
20
32+4=36
B
12
30
36+12=48
Mean flow time =(3+9+11+22+32+36+48)/7 = 23 days
JOB
PROCESSING TIME(DAYS)
DUE DATE
Flow Time
C
2
15
0+2=2
F
3
5
2+3 = 5
A
4
20
5+4=9
G
6
9
9+6=15
E
10
18
15+10=25
D
11
16
25+11=36
B
12
30
36+12=48
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