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Machine Breakdown Recovery - Expert Level: conceptual clarity Machine Breakdown Recovery EXPERT

This skill evaluation ⚡ worksheet focuses on Machine Breakdown Recovery - a key topic in Scheduling. You'll solve 20 expert-level problems (Worksheet 9 of 10). The primary focus is on conceptual clarity. Master machine breakdown recovery ssc cgl, machine breakdown recovery reasoning tricks, and fast machine breakdown recovery solving through systematic practice.

📝 Worksheet 9 of 10 • 20 questions • ⏱️ Estimated time: 20 minutes • 🎯 Expert level

What you'll learn in this worksheet:
Your progress through Machine Breakdown Recovery
Worksheet 9 of 10 (88% complete)

Question 1

A machine needs to process 4 jobs. Processing times: - Job D: 30 minutes - Job E: 53 minutes - Job A: 30 minutes - Job B: 85 minutes The machine breaks down at 118 minutes and takes 38 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 A → Job E → Job B
2. Simulate processing with breakdown:
- Job D: 0 → 30
- Job A: 30 → 60
- Job E: 60 → 113
- Job B: Starts at 113, breakdown at 118 (5 min completed), repair 38 min, resume 80 min → completes at 236

3. Total makespan: 236 minutes
4. Delay caused by breakdown: 38 minutes

Answer: 236 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 C: 76 minutes - Job D: 82 minutes - Job E: 35 minutes - Job B: 63 minutes The machine breaks down at 85 minutes and takes 45 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 B → Job C → Job D
2. Simulate processing with breakdown:
- Job E: 0 → 35
- Job B: Starts at 35, breakdown at 85 (50 min completed), repair 45 min, resume 13 min → completes at 143
- Job C: 143 → 219
- Job D: 219 → 301

3. Total makespan: 301 minutes
4. Delay caused by breakdown: 45 minutes

Answer: 301 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 C: 57 minutes - Job A: 72 minutes - Job E: 83 minutes - Job B: 33 minutes The machine breaks down at 78 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 B → Job C → Job A → Job E
2. Simulate processing with breakdown:
- Job B: 0 → 33
- Job C: Starts at 33, breakdown at 78 (45 min completed), repair 40 min, resume 12 min → completes at 130
- Job A: 130 → 202
- Job E: 202 → 285

3. Total makespan: 285 minutes
4. Delay caused by breakdown: 40 minutes

Answer: 285 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 C: 72 minutes - Job A: 67 minutes - Job D: 43 minutes - Job E: 68 minutes The machine breaks down at 106 minutes and takes 23 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 A → Job E → Job C
2. Simulate processing with breakdown:
- Job D: 0 → 43
- Job A: Starts at 43, breakdown at 106 (63 min completed), repair 23 min, resume 4 min → completes at 133
- Job E: 133 → 201
- Job C: 201 → 273

3. Total makespan: 273 minutes
4. Delay caused by breakdown: 23 minutes

Answer: 273 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 D: 83 minutes - Job A: 71 minutes - Job E: 74 minutes - Job C: 31 minutes The machine breaks down at 109 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 C → Job A → Job E → Job D
2. Simulate processing with breakdown:
- Job C: 0 → 31
- Job A: 31 → 102
- Job E: Starts at 102, breakdown at 109 (7 min completed), repair 43 min, resume 67 min → completes at 219
- Job D: 219 → 302

3. Total makespan: 302 minutes
4. Delay caused by breakdown: 43 minutes

Answer: 302 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 C: 78 minutes - Job D: 79 minutes - Job B: 69 minutes - Job A: 47 minutes The machine breaks down at 109 minutes and takes 45 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 D
2. Simulate processing with breakdown:
- Job A: 0 → 47
- Job B: Starts at 47, breakdown at 109 (62 min completed), repair 45 min, resume 7 min → completes at 161
- Job C: 161 → 239
- Job D: 239 → 318

3. Total makespan: 318 minutes
4. Delay caused by breakdown: 45 minutes

Answer: 318 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 C: 77 minutes - Job D: 64 minutes - Job A: 70 minutes - Job B: 80 minutes The machine breaks down at 89 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 D → Job A → Job C → Job B
2. Simulate processing with breakdown:
- Job D: 0 → 64
- Job A: Starts at 64, breakdown at 89 (25 min completed), repair 24 min, resume 45 min → completes at 158
- Job C: 158 → 235
- Job B: 235 → 315

3. Total makespan: 315 minutes
4. Delay caused by breakdown: 24 minutes

Answer: 315 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 B: 45 minutes - Job E: 59 minutes - Job A: 52 minutes - Job C: 61 minutes The machine breaks down at 85 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 B → Job A → Job E → Job C
2. Simulate processing with breakdown:
- Job B: 0 → 45
- Job A: Starts at 45, breakdown at 85 (40 min completed), repair 40 min, resume 12 min → completes at 137
- Job E: 137 → 196
- Job C: 196 → 257

3. Total makespan: 257 minutes
4. Delay caused by breakdown: 40 minutes

Answer: 257 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: 69 minutes - Job A: 50 minutes - Job B: 51 minutes - Job E: 45 minutes The machine breaks down at 97 minutes and takes 39 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 A → Job B → Job D
2. Simulate processing with breakdown:
- Job E: 0 → 45
- Job A: 45 → 95
- Job B: Starts at 95, breakdown at 97 (2 min completed), repair 39 min, resume 49 min → completes at 185
- Job D: 185 → 254

3. Total makespan: 254 minutes
4. Delay caused by breakdown: 39 minutes

Answer: 254 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: 85 minutes - Job A: 41 minutes - Job B: 44 minutes - Job C: 36 minutes The machine breaks down at 66 minutes and takes 17 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 B → Job E
2. Simulate processing with breakdown:
- Job C: 0 → 36
- Job A: Starts at 36, breakdown at 66 (30 min completed), repair 17 min, resume 11 min → completes at 94
- Job B: 94 → 138
- Job E: 138 → 223

3. Total makespan: 223 minutes
4. Delay caused by breakdown: 17 minutes

Answer: 223 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 B: 53 minutes - Job A: 44 minutes - Job D: 78 minutes - Job E: 69 minutes The machine breaks down at 103 minutes and takes 44 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 E → Job D
2. Simulate processing with breakdown:
- Job A: 0 → 44
- Job B: 44 → 97
- Job E: Starts at 97, breakdown at 103 (6 min completed), repair 44 min, resume 63 min → completes at 210
- Job D: 210 → 288

3. Total makespan: 288 minutes
4. Delay caused by breakdown: 44 minutes

Answer: 288 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 D: 43 minutes - Job E: 66 minutes - Job A: 82 minutes - Job C: 82 minutes The machine breaks down at 108 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 D → Job E → Job A → Job C
2. Simulate processing with breakdown:
- Job D: 0 → 43
- Job E: Starts at 43, breakdown at 108 (65 min completed), repair 32 min, resume 1 min → completes at 141
- Job A: 141 → 223
- Job C: 223 → 305

3. Total makespan: 305 minutes
4. Delay caused by breakdown: 32 minutes

Answer: 305 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 B: 76 minutes - Job D: 39 minutes - Job E: 66 minutes - Job C: 40 minutes The machine breaks down at 60 minutes and takes 38 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 C → Job E → Job B
2. Simulate processing with breakdown:
- Job D: 0 → 39
- Job C: Starts at 39, breakdown at 60 (21 min completed), repair 38 min, resume 19 min → completes at 117
- Job E: 117 → 183
- Job B: 183 → 259

3. Total makespan: 259 minutes
4. Delay caused by breakdown: 38 minutes

Answer: 259 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 A: 55 minutes - Job E: 50 minutes - Job C: 70 minutes - Job D: 45 minutes The machine breaks down at 92 minutes and takes 28 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 A → Job C
2. Simulate processing with breakdown:
- Job D: 0 → 45
- Job E: Starts at 45, breakdown at 92 (47 min completed), repair 28 min, resume 3 min → completes at 123
- Job A: 123 → 178
- Job C: 178 → 248

3. Total makespan: 248 minutes
4. Delay caused by breakdown: 28 minutes

Answer: 248 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 D: 45 minutes - Job E: 61 minutes - Job B: 49 minutes - Job C: 72 minutes The machine breaks down at 103 minutes and takes 42 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 B → Job E → Job C
2. Simulate processing with breakdown:
- Job D: 0 → 45
- Job B: 45 → 94
- Job E: Starts at 94, breakdown at 103 (9 min completed), repair 42 min, resume 52 min → completes at 197
- Job C: 197 → 269

3. Total makespan: 269 minutes
4. Delay caused by breakdown: 42 minutes

Answer: 269 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 A: 49 minutes - Job E: 48 minutes - Job D: 85 minutes - Job C: 78 minutes The machine breaks down at 110 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 A → Job C → Job D
2. Simulate processing with breakdown:
- Job E: 0 → 48
- Job A: 48 → 97
- Job C: Starts at 97, breakdown at 110 (13 min completed), repair 32 min, resume 65 min → completes at 207
- Job D: 207 → 292

3. Total makespan: 292 minutes
4. Delay caused by breakdown: 32 minutes

Answer: 292 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 C: 66 minutes - Job D: 60 minutes - Job B: 80 minutes - Job A: 71 minutes The machine breaks down at 118 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 D → Job C → Job A → Job B
2. Simulate processing with breakdown:
- Job D: 0 → 60
- Job C: Starts at 60, breakdown at 118 (58 min completed), repair 15 min, resume 8 min → completes at 141
- Job A: 141 → 212
- Job B: 212 → 292

3. Total makespan: 292 minutes
4. Delay caused by breakdown: 15 minutes

Answer: 292 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: 42 minutes - Job E: 63 minutes - Job A: 44 minutes - Job D: 85 minutes The machine breaks down at 88 minutes and takes 27 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 E → Job D
2. Simulate processing with breakdown:
- Job B: 0 → 42
- Job A: 42 → 86
- Job E: Starts at 86, breakdown at 88 (2 min completed), repair 27 min, resume 61 min → completes at 176
- Job D: 176 → 261

3. Total makespan: 261 minutes
4. Delay caused by breakdown: 27 minutes

Answer: 261 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 C: 49 minutes - Job D: 70 minutes - Job B: 60 minutes - Job E: 66 minutes The machine breaks down at 97 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 C → Job B → Job E → Job D
2. Simulate processing with breakdown:
- Job C: 0 → 49
- Job B: Starts at 49, breakdown at 97 (48 min completed), repair 36 min, resume 12 min → completes at 145
- Job E: 145 → 211
- Job D: 211 → 281

3. Total makespan: 281 minutes
4. Delay caused by breakdown: 36 minutes

Answer: 281 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 C: 63 minutes - Job B: 90 minutes - Job E: 54 minutes - Job A: 89 minutes The machine breaks down at 98 minutes and takes 25 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 A → Job B
2. Simulate processing with breakdown:
- Job E: 0 → 54
- Job C: Starts at 54, breakdown at 98 (44 min completed), repair 25 min, resume 19 min → completes at 142
- Job A: 142 → 231
- Job B: 231 → 321

3. Total makespan: 321 minutes
4. Delay caused by breakdown: 25 minutes

Answer: 321 minutes

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