Question

decimal places). An Alabama lumberyard has four jobs on order, as shown in the following table. Jobs are logged as they arrive. Today is day 1 on the yard's schedule. In what sequence would the jobs be ranked according to the decision rules on the left: % (enter your response as a percentage The percentage utilization for the sequence developed using the EDD rule = rounded to two decimal places). Job Work (Processing) Time (Days) Job Due Date (Days) d) Using the Critical Ratio (CR) scheduling rule for sequencing the jobs, the order is: Sequence Job The average tardiness (job lateness) for the sequence developed using the CR rule= two decimal places). days (round your response to days (round your response to two The average completion time for the sequence developed using the CR rule = decimal places). % (enter your response as a percentage The percentage utilization for the sequence developed using the CR rule = rounded to two decimal places).

Answer 1

Critical Ratio (CR) for job A = Job due date/ Processing Time = 5/3 = 1.67

CR for job B= 4/4 =1

CR for job C = 6/8 = 0.75

CR for job D = 8/5 = 1.60

So, the sequence of jobs would be from lowest CR to highest CR i.e. C, B, D, A

Jobs	Process Time	Due Date	Lateness = Process Time - Due Date
C	8	6	2
B	4+8=12	4	8
D	5 + 12 =17	8	9
A	3 + 17 =20	5	15
Total	57		34

Average Lateness = 34/5 = 6.77 = 7 days

Average Completion Time = 57/5 = 11.4 = 11 days

Percentage Utilization = Normal Time taken/ Actual Time taken due to scheduling = 20/57 = .35 = 35%