Interviewer view · keep this screen to yourself

Store shelf or own website: contribution per serum in each channel

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.

Lumora (fictional) can sell its USD 60 serum through the specialty retailer (it receives USD 33) or on its own website at the full USD 60. Making the serum costs USD 8.58 either way. On the website, delivery and packing cost USD 6 per order, payment fees are 3 percent of the price, and online advertising costs USD 15 for each order it wins. Which channel leaves more per serum before shared costs, and what happens if the advertising cost per order rises to USD 25?

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.

Contribution per unit in each channel = price received minus costs that come with that sale
- Retail: net price minus cost of goods
- Direct: full price minus cost of goods, delivery, payment fee and advertising per order
- Test: the advertising cost per order is the swing factor

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: Retail contribution
What a strong candidate does: USD 33 received minus USD 8.58 of goods.
Retail contribution per serum (USD): 33 - 8.58 = 24.42
Step 2: Payment fee online
What a strong candidate does: 3 percent of USD 60.
Payment fee (USD): 60 × 0.03 = 1.8
Step 3: Direct contribution
What a strong candidate does: USD 60 minus goods, delivery, payment fee and USD 15 of advertising.
Direct contribution per serum (USD): 60 - 8.58 - 6 - 1.8 - 15 = 28.62
Step 4: Direct contribution with dearer advertising
What a strong candidate does: The same sum with USD 25 of advertising per order.
Direct contribution at USD 25 per order (USD): 60 - 8.58 - 6 - 1.8 - 25 = 18.62

The recommendation to listen for

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

Lumora should keep the retailer as its main channel and use its website for repeat buyers, because direct selling wins only while advertising costs stay low: USD 28.62 per serum against USD 24.42 at USD 15 of advertising per order, but USD 18.62 at USD 25. First, the retailer brings shoppers without paying per order. Second, repeat buyers on the website cost far less to win again, so direct selling suits loyal customers. The risk is that platforms raise advertising prices, which has happened often. As a next step, measure how many orders each new online buyer places in a year.

Risks a strong answer names: Rising advertising prices on social platforms; Returns and damaged parcels add costs not counted here.

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.