Interviewer view · keep this screen to yourself

Why drivers go where the riders are, and what it costs to fight that

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

Target length:

1. Read the prompt aloud

Read it slowly, then pause. Let the candidate ask questions before they structure.

Illustrative numbers, fictional apps. In a city in Singapore, drivers on the larger ride app, App B, carry a passenger for 45 minutes of each hour online, because riders are everywhere. Drivers on the smaller App A carry a passenger for only 30 minutes of each hour. On both apps a driver keeps SGD 0.80 for each minute with a passenger. How much more does a driver earn per hour on App B, and what would App A have to spend in bonuses to match it for 2,000 drivers working 40 hours a week?

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.

Driver earnings per hour = busy minutes per hour x earnings per busy minute
- Compare the two apps
- Cost to match = gap per hour x drivers x hours

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: App A earnings
What a strong candidate does: 30 busy minutes at SGD 0.80.
App A driver earnings (SGD per hour): 30 × 0.8 = 24
Step 2: App B earnings
What a strong candidate does: 45 busy minutes at SGD 0.80.
App B driver earnings (SGD per hour): 45 × 0.8 = 36
Step 3: The gap
What a strong candidate does: The extra a driver earns on App B every hour.
Earnings gap (SGD per hour): 45 × 0.8 - 30 × 0.8 = 12
Step 4: Weekly cost to match
What a strong candidate does: SGD 12 an hour, for 2,000 drivers, for 40 hours.
Bonus cost (SGD per week): 12 × 2,000 × 40 = 960,000
Step 5: Yearly cost to match
What a strong candidate does: Fifty-two weeks.
Bonus cost (SGD per year): 960,000 × 52 = 49,920,000

The recommendation to listen for

At the end, say: "The CEO walks in. What is your recommendation?"

A driver earns SGD 36 an hour on the bigger app against SGD 24 on the smaller one, only because the bigger app keeps drivers busier. To match it, App A would have to pay about SGD 50 million a year in bonuses for just 2,000 drivers, and the moment it stops, drivers drift back. That is the economics of a network effect: the leader gets the same result for free that the follower must buy. App A's better options are to win one district or one niche where it can be the denser network, or to combine with a rival.

Risks a strong answer names: If drivers run both apps at once, the gap shrinks, because App A can borrow App B's drivers; Network effects are local: winning one city says little about the next one.

Score the candidate

Score each criterion from 1 to 5. A 2 or a 4 sits between the descriptions.

This case has no exhibit. Score Exhibit reading on how the candidate used the data you gave them: did they pick out the number that matters and say what it means?

Structuring

1: No clear structure, or a memorized framework that does not fit the problem.
3: A sensible structure, but with some overlap, a gap, or no clear priority.
5: A structure built for this problem, with no overlap and no gaps, a stated hypothesis, and a clear first step.

Math

1: Frequent errors, no units, or needed heavy help to finish.
3: Right answers but slow or messy working, or one error caught late.
5: Accurate and clearly narrated, with units, a sense check, and what the number means.

Exhibit reading

1: Read the chart aloud without finding the number that matters.
3: Found the key number but gave only part of the so-what.
5: Pulled the right number quickly and said what it means for the case.

Synthesis

1: Summarized what was done, with no clear answer.
3: Gave an answer, but with weak reasons or no next step.
5: Answer first, then two or three reasons with numbers, the main risk, and next steps.

Communication

1: Hard to follow: long silences, no signposting.
3: Clear most of the time, with some rambling.
5: Calm and concise, signposted each step, and checked in with the interviewer.

Total

0 out of 25

Score all five criteria to see the band and the feedback template.