Interviewer view · keep this screen to yourself
A parcel hub in Dubai that cannot cope with peak season
You run the case. Read the prompt, answer questions from the notes below, and share data only when the candidate asks for it or gets stuck. Score at the end.
Case timer
00:00
1. Read the prompt aloud
Read it slowly, then pause. Let the candidate ask questions before they structure.
Interviewer: "A delivery company runs a parcel hub in Dubai, open 20 hours a day. In the 90-day peak season, 200,000 parcels arrive a day. The hub cannot handle them all, so the overflow goes to a subcontractor, which costs AED 5 more per parcel. The step capacities are in the table with this case. Management wants to buy an automated sorter for AED 40 million. What do you recommend?" (Fictional company, illustrative figures.)
The prompt refers to Exhibit 1. After reading it, say: "Open Exhibit 1 now."
2. Answers to clarifying questions
This case has no scripted clarifying answers. Answer from the prompt, and say "assume what you think is reasonable" if the prompt does not cover it.
3. A model structure
Compare the candidate's structure with this one. A different split can be just as good if it is clean and fits the problem.
- Overflow cost = (peak demand minus hub output) x peak days x AED 5
- Hub output = the lower of demand and the slowest step
- Key: Cheap fix first: raise the sorting lines' OEE
- Then the sorter: net saving and payback
- Downside: what if peak volume is lower?
Exhibit 1
The prompt uses this exhibit, so the candidate opens it right after you read the prompt ("Show exhibit 1" on their screen).
| Step | Parcels per hour | Parcels per day (20 hours) |
|---|---|---|
| Unload trucks | 12,000 | 240,000 |
| Sort (manual lines) | 8,000 | 160,000 |
| Load delivery vans | 11,000 | 220,000 |
So-what
Sorting is the bottleneck at 160,000 a day, 40,000 short of peak demand.
4. The working, step by step
Each step shows how a strong candidate works it out. Share a new fact from it only when the candidate asks or is stuck, and let them do the math: the result in the dark box is what they should reach.
Step 1: Pin the question and find the bottleneck
What a strong candidate does: The goal is to stop paying for overflow at the lowest total cost. Output is the lowest of demand and the three steps; sorting limits the hub.
Hub output today (parcels a day): min(200,000; 12,000 × 20; 8,000 × 20; 11,000 × 20) = 160,000
Step 2: Cost of the problem
What a strong candidate does: 40,000 overflow parcels a day, for 90 days, at AED 5 each, in AED millions.
Overflow cost a year (AED millions): (200,000 - 160,000) × 90 × 5 ÷ 1,000,000 = 18
Step 3: Cheap fix first
What a strong candidate does: The interviewer says the lines lose about an hour in eight to jams and restarts. Fixing chutes and training (AED 2 million once) lifts sorting from 8,000 to 9,000 an hour.
Overflow cost after the fix (AED millions): (200,000 - 9,000 × 20) × 90 × 5 ÷ 1,000,000 = 9
Step 4: Payback of the cheap fix
What a strong candidate does: AED 2 million against AED 9 million saved a year, in months.
Payback of the fix (months): 2 ÷ (18 - 9) × 12 = 2.67
Step 5: The sorter after the fix
What a strong candidate does: It adds 6,000 an hour. That removes the remaining AED 9 million of overflow and saves AED 4 million a year of manual sorting outside the peak. It costs AED 3 million a year to run.
Net saving of the sorter (AED millions a year): 9 + 4 - 3 = 10
Step 6: Payback of the sorter
What a strong candidate does: AED 40 million divided by 10 million a year.
Payback of the sorter (years): 40 ÷ (9 + 4 - 3) = 4
Step 7: Downside: peak of 175,000 a day
What a strong candidate does: After the cheap fix the hub handles 180,000, so there is no overflow left for the sorter to remove. Only the AED 4 million labour saving is left, minus AED 3 million to run.
Payback of the sorter in the downside (years): 40 ÷ (max(0; 175,000 - 9,000 × 20) × 90 × 5 ÷ 1,000,000 + 4 - 3) = 40
Step 8: The next limit
What a strong candidate does: With the fix and the sorter, sorting reaches 15,000 an hour, and loading becomes the slowest step.
Hub capacity with the sorter (parcels a day): min(12,000; 9,000 + 6,000; 11,000) × 20 = 220,000
The recommendation to listen for
At the end, say: "The CEO walks in. What is your recommendation?"
Do the cheap fix now, and decide on the sorter only when volume justifies it. Cutting jams on the manual sorting lines costs AED 2 million. It halves the overflow bill from AED 18 million to 9 million a year and pays back in under three months. The sorter would then pay back in about 4 years if peak demand stays at 200,000 a day. If peak volume settles at 175,000, it would take about 40 years, because the fixed lines already cope. The main risk is volume, so set a signpost: order the sorter once peak days pass 180,000 parcels. When it comes, loading vans becomes the next limit at 220,000 a day, so plan that step too.
Strong versus weak
A strong answer
Found sorting as the bottleneck from the table. Put a money value on the problem (AED 18 million a year). Fixed the cheapest thing first. Then judged the sorter on payback and on a downside, and named the next bottleneck.
A weak answer
Calculated the sorter's payback at the planned volume and said yes. Did not check whether a cheaper fix could close most of the gap, or what happens if volume is lower.
Score the candidate
Score each criterion from 1 to 5. A 2 or a 4 sits between the descriptions.
Total
0 out of 25
Score all five criteria to see the band and the feedback template.
Next: another case in Partner mode
Swap roles and run the next case, so you both practise answering and scoring.