Question

A furniture company manufactures wooden tables . Management schedules overtime every weekend to reduce the backlog on the most popular models. The automatic routing machine is used to cut certain types of edges on the tables. The following orders need to be scheduled for the routing​ machine:

order	time arrived hours	estimated machine hours	due date hours
1	1	9	20
2	0	7	21
3	6	8	12
4	5	3	8
5	3	12	18

The due dates reflect the need for the order to be at its next operation. Develop separate schedules by using the FCFS and EDD rules. Compare the schedules on the basis of average flow time and average past due hours.

A. Using the FCFS​ (first come, first served​ ) decision rule for sequencing the​ orders, the order​ is

Sequence	1	2	3	4	5
order	3	4	5	1	2

B Using the EDD​ (earliest due​ date) decision rule for sequencing the​ orders, the order is​ (to resolve a​ tie, use order in which the orders were​ received):

Sequence	1	2	3	4	5
Order	4	3	5	1	2

C. The average flow time and average past due hours for each option are ​(enter your responses are real numbers rounded to two decimal

​places)​:

Rule	Average Flow Time	Average Past Due Hours
EDD
FCFS

Answer 1

A. FCFS

Earlier the job arrived, the earlier it will be processed.

Flow time = Cumulative sum of estimated machine hours for completed jobs

Past Due hours = Max (0, Flow time - Due date hours)

Average Flow time = Total Flow time / 5

Average past due hours = Total Past due hours /5

B. EDD - The job with earlier due date will be processed first.

C.

FCFS Sequence Order Time Arrived hours Estimated Machine Hours Due Date Hours Flow time Past Due hours 1 3 6 12 18 12 0 2 4 5 3 8 15 7 3 5 3 8 12 23 11 4 1 1 7 21 30 9 5 2 0 9 20 39 19 Total 39 119 46 23.80 Average Flow time Average Past Due hours 9.20

EDD Estimated Time Arrived Machine hours Hours Flow Sequence Order Due Date Hours Past Due hours time 1 4 5 3 8 3 0 2 1 1 7 21 10 0 3 5 3 8 12 18 6 4 2 0 9 20 27 7 5 3 6 12 18 39 21 Total 39 97 34 19.40 Average Flow time Average Past Due hours 6.80

Rule Average Average Past Flow Time Due Hours 19.40 6.80 23.80 9.20 EDD FCFS