Which order meets the handoff times?
Alder Paper Works, a fictional label shop, must finish four jobs for scheduled handoffs.
The question
The main line starts at minute 0 ready for small labels. A format change takes 20 minutes including the approved check. Same-format jobs need no change. Meet every due time, then finish all four jobs as early as possible.
| A | B | C | D | |
|---|---|---|---|---|
| Format | Small | Large | Small | Large |
| Job duration (minutes) | 70 | 80 | 60 | 50 |
| Due minute | 100 | 230 | 300 | 360 |
Current order is A, B, C, D. Use elapsed minutes from the start of the shift.
“Compare the job sequences, then revise the schedule when a due time and a check change.”
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A strong answer, step by step
Open each step in turn. This is one strong answer, not the only one.
Step 1: When does the current plan finish?
What would you do here? Open the move you’d make.
Add a format change before all four jobs
Tempting, but it misses something. The main line is already ready for A.
Add a change only at each change of format
The strong move. Three changes take 60 minutes and bring the last job to minute 320.
Use only job durations because all jobs start in the same shift
Tempting, but it misses something. That leaves 60 minutes of required changes out of the plan.
See how a strong candidate says it
“A, B, C and D finish at 70, 170, 250 and 320. Three format changes take 60 minutes.”
Why it works: A starts in the ready format. Each subsequent job in this sequence changes format.
Step 2: What does grouping save?
What would you do here? Open the move you’d make.
Group A and C before B and D, then check every due time
The strong move. This saves two changes and meets all four handoffs.
Put both large jobs first to avoid the change between B and D
Tempting, but it misses something. Starting large requires a change and puts A beyond its due time.
Keep the original order because B must always run second
Tempting, but it misses something. In the opening schedule, B can run third and finish at minute 230.
See how a strong candidate says it
“A, C, B and D finish at 70, 130, 230 and 280. One change takes 20 minutes. That saves 40 minutes, and B meets its due time exactly.”
Why it works: The grouped plan changes format once. Check each handoff before choosing it.
Step 3: How do you meet the earlier handoff?
B now has a firm due time of minute 205. The other due times stay the same.
What would you do here? Open the move you’d make.
Keep A, C, B, D because it has the fewest changes
Tempting, but it misses something. B would finish at minute 230 and miss its new deadline.
Run A, B, D, C and check C’s finish
The strong move. B is early enough and C finishes at its due minute.
Use A, B, C, D as the earliest feasible finish
Tempting, but it misses something. It meets the handoffs and finishes 20 minutes later than A, B, D, C.
See how a strong candidate says it
“A, C, B, D misses B by 25 minutes. I would run A, B, D, C. They finish at 70, 170, 220 and 300. All four are on time.”
Why it works: B moves forward. Keeping both large jobs together saves a change after B.
Step 4: Which plan keeps the added check?
A large-to-small change on the main line now needs another 15 minutes for an approved first-unit check. A separate, staffed small line can run only C. It is free from minute 215 and needs 75 minutes for C including review.
What would you do here? Open the move you’d make.
Keep A, B, D, C on the main line with the added check
Tempting, but it misses something. C would finish at minute 315, 15 minutes late.
Return to A, B, C, D on the main line as the fastest feasible plan
Tempting, but it misses something. It meets the due times and finishes at 335, later than the parallel plan.
Run C on the independent line and A, B, D on the main line
The strong move. The two lines have separate staff. The approved work for C ends at 290.
See how a strong candidate says it
“I would assign C to the small line, where it ends at minute 290. On the main line A, B and D finish at 70, 170 and 220. All four are on time with the required checks.”
Why it works: The best feasible main-line-only plan finishes at 335. The independent line completes the order 45 minutes sooner.
The answer, in short
- Decision
- Meet each due time and keep each required check in the schedule.
- Because
- Grouping reduces changes. Due times and available lines determine whether grouping works.
- What would change it
- A change to B’s due time or the small line’s availability would change the plan.
Common traps
- Start with the format that is already ready.
- Compare the last finish only after every job meets its due time.
Check your answer
- I added each change to the timeline.
- I checked B’s earlier due time.
- I allowed time for the new review.
- I stated when the last job finishes.
Last reviewed Nov 11, 2026