Question

4. [10 points] Today is Nov 15. The following jobs need to be scheduled on the same machine. Job Processing Time (Davs) Due Date Nov 30 Dec 22 Nov 18 Dec 3 Nov 29 12 a. Schedule the jobs according to i. Shortest processing time ii. Earliest due date. iii. Longest processing time. b. For the SPT& EED schedules from part a, calculate the average completion time.

Answer 1

The data provided in the question:-

Job	Processing time	Due Date
A	12	Nov 30
B	15	Dec 22
C	3	Nov 18
D	8	Dec 3
E	6	Nov 29

Answer a:-

i:- Shortest processing time:- In order to find out the sequence as per this rule, the job which has the least processing time will be sequenced first and then the remaining jobs will be sequenced in the increasing processing time.

So the job sequence will be as below:-

C-E-D-A-B

ii:- Earliest due date:- In this, the job which has the least due date will be sequenced first followed by the jobs having later due dates.

So the sequence will be:-

C-E-A-D-B

iii:- Longest processing time:- In order to find out the sequence as per this rule, the job which has the maximum processing time will be sequenced first and then the remaining jobs will be sequenced in the decreasing processing time.

So the job sequence will be as below:-

B-A-D-E-C

Answer b:- For Shortest processing time:-

Jobs	Flow in Time	Flow Out time
C	0	0+3=3
E	3	3+6=9
D	9	9+8=17
A	17	17+12=29
B	29	29+15=44

Total Flow time = 3+9+17+29+44=102

Average completion time = Total flow time / number of jobs

Average completion time =102/5

Average completion time =20.4 Days

For Earliest Due Date:-

Jobs	Flow in Time	Flow Out time
C	0	0+3=3
E	3	3+6=9
A	9	9+12=21
D	21	21+8=29
B	29	29+15=44

Total Flow time = 3+9+21+29+44=106

Average completion time = Total flow time / number of jobs

Average completion time =106/5

Average completion time =21.2 Days