CaseLane: AI-powered consulting interview preparation platform for McKinsey, BCG, and Bain interviews.

Skip to the practice case
Caselane

Case interview practice · Open worked examples

Start with a decision.
Build the case for it.

A coffee chain wants higher profit. A delivery partner promises more orders. Should the chain sign?

Work through the problem, read the numbers and compare your recommendation with the reasoning below.

Work through the case

Prompt, exhibits and answers are open. No account needed.

01 / Clarify the objective

What would make delivery worth doing?

Northline Coffee operates ten shops. The owner wants the chain to earn at least $100,000 in monthly operating profit. A delivery platform proposes a chain-wide launch. You have been asked to recommend whether to proceed.

Your task

Before calculating, name the questions you would ask. Separate the objective, the current business and the proposed change.

Compare your clarifying questions
  • Is the target for the entire chain, and is it recurring monthly operating profit?
  • What do current orders, average order value, variable costs and fixed costs look like?
  • Are delivery orders incremental, or will existing customers switch channels?
  • What commission, packaging and extra staffing does delivery require?
  • Can the shops handle the extra volume without damaging the existing service?

For this exercise, use the monthly chain-wide figures below. Exclude tax, financing and one-time launch costs. Those exclusions limit the recommendation; they are not evidence those costs are zero in a real business.

Build a structure around the decision

Start with current profit. Then estimate the incremental contribution from delivery, subtract new fixed costs and any contribution lost from existing orders. Check capacity and service quality before turning the calculation into a launch recommendation.

New profit = current profit + delivery contribution − new fixed costs − lost shop contribution

A named framework is useful only if it helps answer this decision. See the consulting frameworks guide for further reading.

02 / Read the exhibit

Find the profit gap.

Exhibit 1 describes the current chain. All shops are combined; all money is in US dollars.

Exhibit 1 · Current business, per month
MeasureChain total
Orders180,000
Average revenue per order$6.00
Variable cost per order$3.60
Fixed operating costs$360,000
Target operating profit$100,000
Calculate before revealing

What is monthly revenue, contribution and operating profit? How far is the chain from its target?

Check the current profit calculation

Revenue = 180,000 orders × $6 = $1,080,000/month.

Contribution per order = $6 − $3.60 = $2.40. Total contribution = 180,000 × $2.40 = $432,000/month.

Operating profit = $432,000 − $360,000 = $72,000/month. The target gap is $100,000 − $72,000 = $28,000/month.

Reasoning check: contribution pays fixed costs before it becomes profit. Treating the $432,000 as operating profit would miss the objective.

03 / Test the proposal

Does a bigger basket solve the problem?

The delivery platform estimates 30,000 delivery orders per month. Start by assuming they are all incremental. Delivery revenue below is the customer’s order value before commission; ignore taxes and customer delivery fees.

Exhibit 2 · Delivery proposal
MeasureAssumption
New delivery orders / month30,000
Average order revenue$8.00
Variable product cost / order$4.80
Platform commission25% of order revenue
Packaging / order$0.30
Additional fixed staffing / month$8,000
Your task

Calculate delivery contribution per order and the chain’s new monthly profit. Does the proposal reach the target?

Check delivery contribution and profit

Commission = 25% × $8 = $2 per order. Delivery contribution = $8 − $4.80 − $2 − $0.30 = $0.90/order.

Monthly delivery contribution = 30,000 × $0.90 = $27,000. After $8,000 of new fixed staffing, incremental profit is $19,000/month.

Chain profit becomes $72,000 + $19,000 = $91,000/month: a $9,000 shortfall. More revenue helps, but this proposal alone misses the owner’s target.

To close the original $28,000 gap with this cost structure, delivery must contribute $36,000 before staffing. At $0.90/order, that requires 40,000 incremental delivery orders/month, assuming the same costs and sufficient capacity.

Now challenge the strongest assumption.

Suppose 10% of delivery orders replace orders that would otherwise have been bought in a shop. Keep total delivery volume at 30,000 and all other assumptions unchanged. What happens?

Check the channel-switching sensitivity

Displaced shop orders = 10% × 30,000 = 3,000. Their lost contribution = 3,000 × $2.40 = $7,200/month.

Delivery’s net incremental profit is now $19,000 − $7,200 = $11,800/month. Chain profit becomes $83,800/month, $16,200 below target.

For each delivery order, expected lost shop contribution is 10% × $2.40 = $0.24. Effective incremental contribution is $0.90 − $0.24 = $0.66/order. Closing the $28,000 gap plus $8,000 staffing would require at least 54,546 delivery orders/month at that mix.

Commercial implication: order volume, channel switching and capacity need testing. A bigger basket does not automatically mean better economics.

04 / Make a recommendation

What would you tell the owner?

Give a recommendation in your own words before opening the example. State the decision, the supporting numbers, the main risk and the next action.

Compare a defensible recommendation
Do not commit to a chain-wide launch as the solution to the $100k profit target. At 30,000 fully incremental orders, delivery raises monthly profit to $91k; with 10% channel switching, it reaches only $83.8k. Run a limited pilot before committing, test incrementality and staffing, and revisit the terms or volume required to close the gap.

A pilot would test assumptions; these figures do not prove it will succeed. Measure delivery contribution after commission and packaging, displaced shop orders, service times and staffing needs. Check launch costs and capacity before setting commercial go/no-go thresholds.

Delivery can be profitable while still failing this specific target. Rejecting it outright without considering a pilot, or recommending it solely because revenue rises, would skip part of the decision.

Review your reasoning

  • Did you define the target and period?
  • Did you distinguish revenue, contribution and operating profit?
  • Did you count commission and packaging once, with the correct units?
  • Did you challenge whether delivery orders are incremental?
  • Did your recommendation reflect the shortfall and the untested assumptions?

These prompts support self-review. They are not a score, a hiring prediction or a benchmark for interview readiness.

05 / Market-sizing practice

How much do workers spend on takeaway coffee?

Try a second kind of case question. Estimate annual weekday takeaway-coffee spending by working adults in a fictional city. Define the market first, then build a calculation with explicit assumptions.

Exclude weekends, non-workers and employer-provided coffee. For this simplified example, assume one purchased coffee on each buying day. Every input below is fictional, not a city statistic.

Choose assumptions, then compare

  • 100,000 working adults
  • 60% follow an on-site working pattern; the rest buy no coffee within this defined market
  • That group attends 3 days per week × 48 working weeks per year
  • 50% buy one takeaway coffee on those days
  • $4 per coffee
See a worked estimate and sensitivity check

Interpret 60% as the share of working adults with this three-day on-site pattern; the others buy none within the defined market. This avoids counting average daily attendance and three-day attendance twice.

Buying occasions = 100,000 × 60% × 3 × 48 × 50% = 4,320,000 coffees/year.

Annual spend = 4,320,000 × $4 = $17.28 million/year, or roughly $17 million given the rough assumptions.

Holding everything else fixed, a 40% on-site share and $3 price give $8.64m; an 80% share and $5 price give $28.8m. These are illustrative scenarios, not a confidence interval or a researched market range.

Check the output: this estimates spending, not the number of coffee shops, takeaway cups manufactured or Northline’s achievable revenue. To estimate a chain’s opportunity, investigate its geography, competitors, customer access and capacity.

Keep practicing

Choose what to work on next.

If the numbers slowed you down, start with math. If the decision was unclear, revisit your structure and recommendation. Platform practice is available after creating an account; these examples stay open.

Account required for the platform. No signup needed for this page.

Before you practice

How should I use this case on my own?

Read each prompt before revealing the reasoning. Write your structure, show the calculation with units, then state a recommendation aloud. Compare the logic rather than memorizing the example wording.

Can I use the case with a practice partner?

Yes. One person can read the prompt and exhibits while the other works through the decision. Discuss what changed when channel switching was introduced. Both can read the worked reasoning without an account.

Are these real McKinsey, BCG or Bain questions?

No. These are original fictional Caselane examples. They are not reported employer questions, endorsed preparation material or predictions of what an interviewer will ask.

Does finishing this page mean I am interview-ready?

No. One worked case cannot establish readiness. Practice unfamiliar problems, seek specific feedback and review how you structure, calculate, interpret and communicate. This page does not grade or certify you.

Original examples by Caselane · Reviewed October 16, 2026.
All business and market-sizing inputs are fictional teaching assumptions.

Caselane homePrivacy