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Machine Breakdown Recovery Beginner-Intermediate Worksheet: Focus on common variations practice Machine Breakdown Recovery BEGINNER INTERMEDIATE

Level up your Machine Breakdown Recovery skills! You're at Worksheet 4 of 10 (33% through this series). This step-up challenge worksheet features 20 beginner-intermediate-level problems with a focus on common variations practice. Topics covered: machine breakdown recovery for competitive exams, how to solve machine breakdown recovery, machine breakdown recovery tricks.

📝 Worksheet 4 of 10 • 20 questions • ⏱️ Estimated time: 20 minutes • 🎯 Beginner Intermediate level

What you'll learn in this worksheet:
Your progress through Machine Breakdown Recovery
Worksheet 4 of 10 (33% complete)

Question 1

A machine needs to process 4 jobs. Processing times: - Job C: 48 minutes - Job A: 40 minutes - Job D: 61 minutes - Job B: 58 minutes The machine breaks down at 87 minutes and takes 24 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job A → Job C → Job B → Job D
2. Simulate processing with breakdown:
- Job A: 0 → 40
- Job C: Starts at 40, breakdown at 87 (47 min completed), repair 24 min, resume 1 min → completes at 112
- Job B: 112 → 170
- Job D: 170 → 231

3. Total makespan: 231 minutes
4. Delay caused by breakdown: 24 minutes

Answer: 231 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 2

A machine needs to process 4 jobs. Processing times: - Job B: 90 minutes - Job A: 76 minutes - Job C: 32 minutes - Job E: 80 minutes The machine breaks down at 97 minutes and takes 15 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job C → Job A → Job E → Job B
2. Simulate processing with breakdown:
- Job C: 0 → 32
- Job A: Starts at 32, breakdown at 97 (65 min completed), repair 15 min, resume 11 min → completes at 123
- Job E: 123 → 203
- Job B: 203 → 293

3. Total makespan: 293 minutes
4. Delay caused by breakdown: 15 minutes

Answer: 293 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 3

A machine needs to process 4 jobs. Processing times: - Job A: 89 minutes - Job E: 56 minutes - Job D: 54 minutes - Job C: 80 minutes The machine breaks down at 107 minutes and takes 36 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job D → Job E → Job C → Job A
2. Simulate processing with breakdown:
- Job D: 0 → 54
- Job E: Starts at 54, breakdown at 107 (53 min completed), repair 36 min, resume 3 min → completes at 146
- Job C: 146 → 226
- Job A: 226 → 315

3. Total makespan: 315 minutes
4. Delay caused by breakdown: 36 minutes

Answer: 315 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 4

A machine needs to process 4 jobs. Processing times: - Job D: 51 minutes - Job A: 61 minutes - Job B: 83 minutes - Job E: 45 minutes The machine breaks down at 60 minutes and takes 34 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job E → Job D → Job A → Job B
2. Simulate processing with breakdown:
- Job E: 0 → 45
- Job D: Starts at 45, breakdown at 60 (15 min completed), repair 34 min, resume 36 min → completes at 130
- Job A: 130 → 191
- Job B: 191 → 274

3. Total makespan: 274 minutes
4. Delay caused by breakdown: 34 minutes

Answer: 274 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 5

A machine needs to process 4 jobs. Processing times: - Job A: 36 minutes - Job E: 84 minutes - Job B: 40 minutes - Job C: 63 minutes The machine breaks down at 100 minutes and takes 21 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job A → Job B → Job C → Job E
2. Simulate processing with breakdown:
- Job A: 0 → 36
- Job B: 36 → 76
- Job C: Starts at 76, breakdown at 100 (24 min completed), repair 21 min, resume 39 min → completes at 160
- Job E: 160 → 244

3. Total makespan: 244 minutes
4. Delay caused by breakdown: 21 minutes

Answer: 244 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 6

A machine needs to process 4 jobs. Processing times: - Job D: 41 minutes - Job E: 44 minutes - Job C: 60 minutes - Job B: 57 minutes The machine breaks down at 96 minutes and takes 33 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job D → Job E → Job B → Job C
2. Simulate processing with breakdown:
- Job D: 0 → 41
- Job E: 41 → 85
- Job B: Starts at 85, breakdown at 96 (11 min completed), repair 33 min, resume 46 min → completes at 175
- Job C: 175 → 235

3. Total makespan: 235 minutes
4. Delay caused by breakdown: 33 minutes

Answer: 235 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 7

A machine needs to process 4 jobs. Processing times: - Job A: 48 minutes - Job E: 56 minutes - Job C: 83 minutes - Job B: 74 minutes The machine breaks down at 100 minutes and takes 33 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job A → Job E → Job B → Job C
2. Simulate processing with breakdown:
- Job A: 0 → 48
- Job E: Starts at 48, breakdown at 100 (52 min completed), repair 33 min, resume 4 min → completes at 137
- Job B: 137 → 211
- Job C: 211 → 294

3. Total makespan: 294 minutes
4. Delay caused by breakdown: 33 minutes

Answer: 294 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 8

A machine needs to process 4 jobs. Processing times: - Job D: 73 minutes - Job A: 76 minutes - Job C: 57 minutes - Job B: 58 minutes The machine breaks down at 93 minutes and takes 35 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job C → Job B → Job D → Job A
2. Simulate processing with breakdown:
- Job C: 0 → 57
- Job B: Starts at 57, breakdown at 93 (36 min completed), repair 35 min, resume 22 min → completes at 150
- Job D: 150 → 223
- Job A: 223 → 299

3. Total makespan: 299 minutes
4. Delay caused by breakdown: 35 minutes

Answer: 299 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 9

A machine needs to process 4 jobs. Processing times: - Job D: 42 minutes - Job A: 39 minutes - Job E: 70 minutes - Job C: 66 minutes The machine breaks down at 105 minutes and takes 43 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job A → Job D → Job C → Job E
2. Simulate processing with breakdown:
- Job A: 0 → 39
- Job D: 39 → 81
- Job C: Starts at 81, breakdown at 105 (24 min completed), repair 43 min, resume 42 min → completes at 190
- Job E: 190 → 260

3. Total makespan: 260 minutes
4. Delay caused by breakdown: 43 minutes

Answer: 260 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 10

A machine needs to process 4 jobs. Processing times: - Job E: 46 minutes - Job D: 45 minutes - Job B: 70 minutes - Job C: 58 minutes The machine breaks down at 76 minutes and takes 20 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job D → Job E → Job C → Job B
2. Simulate processing with breakdown:
- Job D: 0 → 45
- Job E: Starts at 45, breakdown at 76 (31 min completed), repair 20 min, resume 15 min → completes at 111
- Job C: 111 → 169
- Job B: 169 → 239

3. Total makespan: 239 minutes
4. Delay caused by breakdown: 20 minutes

Answer: 239 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 11

A machine needs to process 4 jobs. Processing times: - Job C: 43 minutes - Job A: 35 minutes - Job B: 52 minutes - Job E: 64 minutes The machine breaks down at 101 minutes and takes 40 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job A → Job C → Job B → Job E
2. Simulate processing with breakdown:
- Job A: 0 → 35
- Job C: 35 → 78
- Job B: Starts at 78, breakdown at 101 (23 min completed), repair 40 min, resume 29 min → completes at 170
- Job E: 170 → 234

3. Total makespan: 234 minutes
4. Delay caused by breakdown: 40 minutes

Answer: 234 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 12

A machine needs to process 4 jobs. Processing times: - Job A: 50 minutes - Job E: 58 minutes - Job C: 85 minutes - Job D: 64 minutes The machine breaks down at 120 minutes and takes 40 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job A → Job E → Job D → Job C
2. Simulate processing with breakdown:
- Job A: 0 → 50
- Job E: 50 → 108
- Job D: Starts at 108, breakdown at 120 (12 min completed), repair 40 min, resume 52 min → completes at 212
- Job C: 212 → 297

3. Total makespan: 297 minutes
4. Delay caused by breakdown: 40 minutes

Answer: 297 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 13

A machine needs to process 4 jobs. Processing times: - Job D: 88 minutes - Job A: 45 minutes - Job B: 31 minutes - Job C: 65 minutes The machine breaks down at 93 minutes and takes 16 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job B → Job A → Job C → Job D
2. Simulate processing with breakdown:
- Job B: 0 → 31
- Job A: 31 → 76
- Job C: Starts at 76, breakdown at 93 (17 min completed), repair 16 min, resume 48 min → completes at 157
- Job D: 157 → 245

3. Total makespan: 245 minutes
4. Delay caused by breakdown: 16 minutes

Answer: 245 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 14

A machine needs to process 4 jobs. Processing times: - Job D: 58 minutes - Job A: 37 minutes - Job C: 39 minutes - Job E: 68 minutes The machine breaks down at 115 minutes and takes 33 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job A → Job C → Job D → Job E
2. Simulate processing with breakdown:
- Job A: 0 → 37
- Job C: 37 → 76
- Job D: Starts at 76, breakdown at 115 (39 min completed), repair 33 min, resume 19 min → completes at 167
- Job E: 167 → 235

3. Total makespan: 235 minutes
4. Delay caused by breakdown: 33 minutes

Answer: 235 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 15

A machine needs to process 4 jobs. Processing times: - Job B: 75 minutes - Job C: 63 minutes - Job E: 55 minutes - Job D: 75 minutes The machine breaks down at 61 minutes and takes 34 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job E → Job C → Job B → Job D
2. Simulate processing with breakdown:
- Job E: 0 → 55
- Job C: Starts at 55, breakdown at 61 (6 min completed), repair 34 min, resume 57 min → completes at 152
- Job B: 152 → 227
- Job D: 227 → 302

3. Total makespan: 302 minutes
4. Delay caused by breakdown: 34 minutes

Answer: 302 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 16

A machine needs to process 4 jobs. Processing times: - Job C: 31 minutes - Job A: 52 minutes - Job B: 88 minutes - Job D: 36 minutes The machine breaks down at 90 minutes and takes 31 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job C → Job D → Job A → Job B
2. Simulate processing with breakdown:
- Job C: 0 → 31
- Job D: 31 → 67
- Job A: Starts at 67, breakdown at 90 (23 min completed), repair 31 min, resume 29 min → completes at 150
- Job B: 150 → 238

3. Total makespan: 238 minutes
4. Delay caused by breakdown: 31 minutes

Answer: 238 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 17

A machine needs to process 4 jobs. Processing times: - Job D: 48 minutes - Job C: 39 minutes - Job E: 33 minutes - Job B: 51 minutes The machine breaks down at 77 minutes and takes 32 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job E → Job C → Job D → Job B
2. Simulate processing with breakdown:
- Job E: 0 → 33
- Job C: 33 → 72
- Job D: Starts at 72, breakdown at 77 (5 min completed), repair 32 min, resume 43 min → completes at 152
- Job B: 152 → 203

3. Total makespan: 203 minutes
4. Delay caused by breakdown: 32 minutes

Answer: 203 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 18

A machine needs to process 4 jobs. Processing times: - Job B: 54 minutes - Job D: 59 minutes - Job C: 32 minutes - Job E: 87 minutes The machine breaks down at 69 minutes and takes 18 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job C → Job B → Job D → Job E
2. Simulate processing with breakdown:
- Job C: 0 → 32
- Job B: Starts at 32, breakdown at 69 (37 min completed), repair 18 min, resume 17 min → completes at 104
- Job D: 104 → 163
- Job E: 163 → 250

3. Total makespan: 250 minutes
4. Delay caused by breakdown: 18 minutes

Answer: 250 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 19

A machine needs to process 4 jobs. Processing times: - Job D: 63 minutes - Job E: 80 minutes - Job B: 34 minutes - Job C: 69 minutes The machine breaks down at 92 minutes and takes 32 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job B → Job D → Job C → Job E
2. Simulate processing with breakdown:
- Job B: 0 → 34
- Job D: Starts at 34, breakdown at 92 (58 min completed), repair 32 min, resume 5 min → completes at 129
- Job C: 129 → 198
- Job E: 198 → 278

3. Total makespan: 278 minutes
4. Delay caused by breakdown: 32 minutes

Answer: 278 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.

Question 20

A machine needs to process 4 jobs. Processing times: - Job A: 55 minutes - Job B: 52 minutes - Job E: 88 minutes - Job C: 82 minutes The machine breaks down at 112 minutes and takes 35 minutes to repair. Jobs are scheduled using Shortest Processing Time (SPT) first rule. What is the total completion time (makespan) after handling the breakdown?
Step-by-step solution (Breakdown Recovery):

1. Original SPT order: Job B → Job A → Job C → Job E
2. Simulate processing with breakdown:
- Job B: 0 → 52
- Job A: 52 → 107
- Job C: Starts at 107, breakdown at 112 (5 min completed), repair 35 min, resume 77 min → completes at 224
- Job E: 224 → 312

3. Total makespan: 312 minutes
4. Delay caused by breakdown: 35 minutes

Answer: 312 minutes

Key Strategy: Simulate the timeline, account for breakdown during active job processing.
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