Part 1 . Question 1. How many of the statements are true? (A) 0 (B) 1 (C) 2 (D)
ID: 347671 • Letter: P
Question
Part 1. Question 1. How many of the statements are true?
(A) 0 (B) 1 (C) 2 (D) 3 (E) 4
Statement 1. The Johnson’s rule is a sequencing rule for an ‘nx2’ system.
Statement 2. The total flow time is minimized in an ‘nx1’ system when the schedule is based on the MPT sequencing rule.
Statement 3. The processing time for a job is equal to the flow time plus the queue time.
Statement 4. The start date for a job is equal to the due date plus the processing time.
Part 2. Questions 2-3
Five jobs arrived to be processed with the processing times and due dates.
Present Date=
280
Work Order
A
B
C
D
E
Processing Time (Days)
22
20
5
4
12
Due Date
320
312
296
298
302
Question 2. The FIFO schedule is “ABCDE” and the LIFO schedule is “EDCBA”.
Consider the schedules based on the sequencing rules: Minimum Processing Time (MPT); Earliest Due Date (EDD); Minimum Slack Time (MST); and Minimum Critical Ratio (MCR). How many of the schedules are correct?
(A) 0 (B) 1 (C) 2 (D) 3 (E) 4
The schedule based on the MPT sequencing rule is D,C,E,B,A
The schedule based on the EDD sequencing rule is C,D,E,B,A
The schedule based on the MST sequencing rule is E,C,B,D,A
The schedule based on the MCR sequencing rule is B,E,A,C,D
Question 3. What is the flow of the MPT schedule?
(A) 138 (B) 63 (C) 233 (D) 230 (E) none of the above
Part 3. Questions 4-5
The jobs A,B,C,D,E, arrived in that order to be processed on two machines.
Job
A
B
C
D
E
Time on Machine 1
27
35
45
13
57
Time on Machine 2
24
47
43
35
59
Question 4. Which is the Johnson’s Rule schedule?
(A) ‘DBECA’ (B) ‘ACEBD’ (C) ‘DCABE’ (D) ‘DABEC’ (E) none of the above
Question 5. How many of the statements are correct for the FIFO schedule of (A,B,C,D,E)?
(A) 0 (B) 1 (C) 2 (D) 3 (E) 4
Statement 1. The total time of completion is 236
Statement 2. The flow time of job D is 187
Statement 3. The total queue time of job C is 64
Statement 4. The total idle time of machine 2 is 38
Present Date=
280
Work Order
A
B
C
D
E
Processing Time (Days)
22
20
5
4
12
Due Date
320
312
296
298
302
Explanation / Answer
PART 1.
Question 1. (B) 1
Only first statement is correct. Statement 1. The Johnson’s rule is a sequencing rule for an ‘nx2’ system.
PART 2.
Question 2. (D) 3
MPT, EDD, MST schedules are correct. MPT and EDD are in the ascending order of Processing time and Due date respectively. MST required calculation of slack time and then scheduling the jobs in ascending order of slack time. Slack time = Due date - Processing time.
MCR requires calculation of Critical ratio, which is ratio of (Due date - current date) and the processing time. Jobs are arranged as per ascending order of MCR. The correct schedule as per MCR is B,A,E,C,D
Question 3. B (63)
Flowtime is 63
Question 4. (A) 'DBECA'
Using Johnson's rule, Select the job with the shortest processing time, if that activity is for Operation 1, then schedule the job first, if that activity is for Operation 2, then schedule the job last. Remove the jobs which are scheduled from further consideration. Repeat the process until all jobs are scheduled.
Optimal schedule using Johnson's rule is as follows
Question 5. A (0)
None of the statements are correct.
Stmt 1: Total time of completion is 231
Stmt 2: Flow time of job D is 48
Stmt 3: Total queue time of job C is 164
Stmt 4: Total idle time of Machine 2 is 231-Sum of processing times = 231-208 = 23
Work Order Processing Time (Days) Due Date Time until Due date D 4 298 4 C 5 296 9 E 12 302 21 B 20 312 41 A 22 320 63