Part 3. Questions 4-8 The jobs A,B,C,D,E, arrived in that order to be processed

Question

Part 3. Questions 4-8 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 62 54 64 52 61

Time on Machine 2 51 66 53 68 57

Question 4. The Johnson’s rule schedule is (A) ‘DBECA’ (B) ‘CEBAD’ (C) ‘DCABE’ (D) ‘DABEC’

Question 5. In the FIFO schedule, what is the total time of completion? (A) 360 (B) 303 (C) 588 (D) None of the above

Question 6. In the FIFO schedule, what is the flow time of job D? (A) 300 (B) 303 (C) 120 (D) None of the above

Question 7. In the FIFO schedule, what is the total queue time of job C? (A) 114 (B) 116 (C) 118 (D) None of the above

Question 8. In the FIFO schedule, what is the total idle time of machine 2? (A) 3 (B) 65 (C) 62 (D) None of the above

Explanation / Answer

Machine 1 Machine 2 A 62 51 B 54 66 C 64 53 D 52 68 E 61 57 The order of Job using Johnson's Rule is D B E C A 1. The Job A has lowest time with operator 2, hence allocated at last 2. The next lowest time is for Job D with operator 1, hence allocated at first 3. The next lowest time is for Job C with operator 2, hence allocated before A 4. The next lowest time is for Job B with operator 1, hence allocated after D 5. The leftover Job E is Allocated. Hence, the correct answer is Option A 5. Total Time of Completion - Option A - 360 Job Machine 1 Machine 2 Machine 1 Machine 2 Cum Time Cum Time A 62 51 62 113 B 54 66 116 182 C 64 53 180 235 D 52 68 232 303 E 61 57 293 360 Machine 2 Cumulative Time Calculation A = 62+51 = 113 B = Max(113,116) + 66 = 182 C = Max(180,182) + 53 = 235 D = Max(235,232) + 68 = 303 E = Max(3033,293) + 57 = 360 6. Flow time of Job D - Option D - None of the above Completion Time - Start Time = 303 - 180 = 123 days or, Job Time of both Machines + Idle Time + Queue Time = (52 + 68) + 0 + 3 = 123 days 7. Queue Time of Job C - Option C - 118 Completion Time - Time Required to be processed = 235 - (64 + 53) = 118 days 8. Idle Time of Machine 2 - Option B - 65 Job Machine 1 Machine 2 Machine 1 Machine 2 Waiting Time Cum Time Cum Time Machine 2 a b c d Note A 62 51 62 113 62 B 54 66 116 182 3 C 64 53 180 235 0 D 52 68 232 303 0 E 61 57 293 360 0 Idle Time Calculation = Cumulative Time for current job - Cumu Time till previous job - Machine 2 Process time for current job Calculations Job A = 113 - 0 - 51 = 62 Job B = 182 - 113 - 66 = 3 Job C = 235 - 182 -53 = 0 Job D = 303 - 235 - 68 = 0 Job E = 360 - 303 - 57 = 0

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