Profitability Case Interview Example With Worked Answer

A profitability case interview example is a full practice case in which a company's profit has fallen and you must find out why and what to do. This profitability case study example is solved start to finish: Ashgrove Car Wash's profit fell from $34M to $22M while revenue stayed at $200M, and both exhibits reconcile to that same $12M drop.

This guide covers the case prompt, the clarifying questions, both exhibits, the math line by line and the recommendation to the CEO.

The case prompt: Ashgrove Car Wash

Ashgrove Car Wash is a made-up client with made-up numbers, built so the arithmetic is easy to check. Read the prompt and take two minutes to write your own questions before you look at the next section.

Prompt. Ashgrove Car Wash runs 40 tunnel car washes across the Southeast and Midwest of the United States. Last year its operating profit fell from $34M to $22M, even though revenue stayed at $200M. The CEO asks: why did profit fall, and what should Ashgrove do about it?

Ashgrove sells three things: a single pay-per-wash, an unlimited monthly membership, and add-ons such as wax, ceramic coating and interior cleaning. Out loud, your first move is to repeat the objective and the numbers back: "Profit down $12M, margin from 17% to 11%, revenue flat, 40 sites. I would like to understand what changed underneath a flat top line."

Profitability case practice at a glance

How a profitability case works: profit fell or stalled, so you split it into revenue and cost, segment until one driver stands out, size it from the exhibits and recommend a fix. The framework itself lives on the profitability framework page; this page is the worked case.

Practice it live: GreenBite Snacks Profitability Reset is an easy profitability case with a different client and its own data: earnings fell while sales barely moved. It has 6 questions, 2 with math, 2 exhibits, and a median of 16 minutes across 56 completed voice runs. An AI interviewer runs it out loud, shows each exhibit when you reach it and scores the debrief. Your first full case is free when you create an account.

Case (style, industry)	Quant difficulty	Qualitative difficulty	The math you run	Median time
AuroraWater Bottling Margin Recovery (McKinsey, packaged beverages). 8 (4 with math), 4 exhibits.packaged beveragesQuant difficulty mediumQualitative difficulty medium22 min· 19 voice runsTry free	medium	medium	Unit-cost savings, EBITDA bridge	22 min19 voice runs22 min, 19 voice runs	Try free
Voltigo FastCharge Turnaround (McKinsey, EV charging). 7 (3 with math), 3 exhibits.EV chargingQuant difficulty mediumQualitative difficulty medium23 min· 13 voice runsTry free	medium	medium	Loss split, hub energy margin, profit	23 min13 voice runs23 min, 13 voice runs	Try free
StyleCraft European Profitability Reset (Bain, stationery). 9 (4 with math), 3 exhibits.stationeryBainQuant difficulty hardQualitative difficulty hardFewer than 10 runsTry free	hard	hard	Offshore cost savings, market sizing funnel	Fewer than 10 runsFewer than 10 runs	Try free
Slippery Soap Profitability (Bain, personal care). 6 (2 with math), 2 exhibits.personal careBainQuant difficulty easyQualitative difficulty easy15 min· 10 voice runsTry free	easy	easy	Revenue growth, bath bomb unit economics	15 min10 voice runs15 min, 10 voice runs	Try free

One is adapted from a consulting club casebook (Wharton); the rest were written for Road to Offer. More are in the case library, 92 cases in all. Every debrief scores seven categories: structure (25% of the score), quantitative analysis (20%), business judgment (15%), and problem understanding, exhibit reading, communication and synthesis (10% each), with feedback on every question. Median times come from completed runs between June 25 and September 22, 2026, and count runs, not people.

What does a profitability case interview look like?

A profitability case gives you a company whose profit fell, stalled or never arrived, and asks why and what to do. The interviewer wants to see you take profit apart, find the one or two drivers that moved, and recommend a fix that does not break something else. The prompt almost always names a symptom (profit down, margin down, a loss) and hides the cause in a segment. If you want the reusable skeleton first, read the profitability framework and come back; if you want the same skeleton drawn as an issue tree, see the issue tree guide.

Profitability prompts come in four common variants. The first move changes with the variant, so spot it in the first sentence:

This page solves the first variant, because it is the cleanest way to learn the reflex that matters most: never trust a flat total.

Which clarifying questions should you ask, and what do the answers give you?

Good clarifying questions rule branches in or out. Weak ones ask for everything. Here are the six that earn their place, with the interviewer's answers (see the clarifying questions guide for how to choose yours):

Notice what you now know without seeing an exhibit: fixed cost is flat, unit cost is flat, pay-per-wash price is flat. Whatever moved is in volume, mix or the member price. That is a hypothesis you can state before the math: "I think the unlimited plan is pulling in washes at a low price per wash and pulling pay-per-wash customers into it."

How do you structure a profitability case?

Start with profit equals revenue minus cost, then split each side until a branch asks for data. For Ashgrove, revenue is washes times revenue per wash, by customer type, plus add-ons. Cost is a variable cost per wash plus a fixed base. The interviewer has already closed two branches, so the tree below shows where your time goes.

Say why you start with segments: "Revenue is flat and unit cost is flat, so a total hides the answer. I will look at contribution, which is revenue minus variable cost, for each customer type." Contribution is the number a profitability case lives on, because fixed cost does not move with the choice in front of you. If the term is new, the unit economics framework covers it.

Exhibit 1: where did the profit go?

The interviewer hands you one table: washes, revenue and contribution by customer type, last year and this year. Amounts are in millions of dollars; "per wash" figures are dollars.

Read it the way an interviewer wants: totals first, then the biggest mover. Total contribution fell from $112M to $100M, a $12M drop. Fixed cost was flat at $78M, so profit moved by the same amount: $112M minus $78M is $34M, and $100M minus $78M is $22M.

The mover is pay-per-wash: contribution fell $18M ($72M to $54M) because washes fell by 2.0M at $9.00 each. Members added only $6M. Two observations to say out loud: total washes rose from 13.0M to 15.0M, so the company is busier and poorer at once, and members now make up 60.0% of washes, up from 38.5% (9.0 divided by 15.0, against 5.0 divided by 13.0).

Exhibit 2: what explains the $12M, step by step?

Exhibit 1 says where the money went. Exhibit 2 says why, as a profit bridge from last year to this year. Because pay-per-wash price and unit cost did not move, only three effects remain.

The three effects add to -$12M, the same drop as Exhibit 1. That cross-check is the habit to build: when two views of a case disagree, one of your readings is wrong, and finding it is worth more than any recommendation.

So what is the answer? Flat revenue hid two opposing moves. Members grew revenue by $30M ($60M to $90M) while pay-per-wash lost $30M ($120M to $90M), and the new revenue came at a contribution of $4.00 per wash against $9.00 for the old. The unlimited plan was priced so low per wash that growth destroyed profit.

How do you do the math line by line?

Do the bridge on the page, in order, and say each number as you write it. This is what a strong candidate's scratch work looks like:

1. Profit check. $112M - $78M = $34M last year. $100M - $78M = $22M this year. Drop: $12M. Margin: 34 / 200 = 17.0%, 22 / 200 = 11.0%.
2. Per-wash contribution. Pay-per-wash: $15.00 - $6.00 = $9.00. Members last year: $12.00 - $6.00 = $6.00. Members this year: $10.00 - $6.00 = $4.00.
3. Washes that switched. Pay-per-wash lost 8.0M - 6.0M = 2.0M. Members gained 9.0M - 5.0M = 4.0M. Half of 4.0M is 2.0M, matching the survey answer, so the other 2.0M are new.
4. Bridge. 2.0M x ($6.00 - $9.00) = -$6M. 2.0M x $6.00 = +$12M. 9.0M x ($10.00 - $12.00) = -$18M. Sum: -$12M.
5. Sanity check. Does the bridge match Exhibit 1's $12M? Yes. Stop and say so.

For more reps on this kind of arithmetic, see the case interview math practice guide. And if you want to practice the same move on a case with a different client, the practice case below runs exactly this skill: find the segment that moved.

Practice a different profitability case

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What would you recommend to the CEO?

The recommendation is the part most candidates rush. Give it as the answer first, then three reasons, one risk and a next step. This is a 60-second version of what a strong candidate says (see the case interview synthesis guide for the structure):

"My recommendation is to keep the unlimited plan but reprice it, and to take a quarter of a dollar out of the cost of each wash. Profit fell $12M because members now do 60% of our washes at $4.00 of contribution each, while the pay-per-wash customers who used to give us $9.00 moved over. Three reasons. First, a tiered membership, with a basic plan and a premium plan that carries the unlimited usage, lifts revenue per member wash from $10.00 to $11.00, worth $9M on 9.0M washes. Second, reclaiming water and tuning chemical use can cut cost per wash by $0.25 on 15.0M washes, worth $3.75M. Third, neither lever closes a site or touches the $15 price that pay-per-wash customers already accept. The main risk is member churn: if 20% of the repricing uplift is lost, the first lever is worth $7.2M, and the total is about $10.95M, or 91% of the drop. Next step: test the tiered plan in five sites for 60 days and track member churn and washes per member."

Check it: $9.0M x 0.8 = $7.2M; $7.2M + $3.75M = $10.95M; $10.95M / $12M = 91.25%. Profit would land near $32.95M against $34M last year. A good answer says that gap out loud instead of claiming a full recovery.

What does a strong profitability answer look like?

Interviewers score a profitability case on a few repeatable behaviors. Here is how the Ashgrove case separates a strong answer from a weak one, using the same categories our debrief uses:

What are the most common mistakes in a profitability case?

• Trusting a flat total. Flat revenue is the setup for the trap. Segment before you conclude.
• Brainstorming levers before diagnosing. "Raise prices" or "cut costs" with no driver is a guess.
• Confusing profit with profitability. Say whether you are tracking dollars or margin and stick to it.
• Ignoring a closed branch. If the interviewer says unit cost is flat, do not recommend a cost program as lever one.
• Forgetting the cross-check. Two exhibits that do not foot mean a misread. Say "this ties to the $12M" or find the gap.
• Claiming a full recovery. Net out churn, one-time costs and the gap to target.

What does a second profitability case study example look like?

Short mini case, because the pattern repeats with a different twist. Prompt: Hollis Bakery sells through its own shops and, new this year, to wholesale accounts. Sales grew 20%, from $50M to $60M, but profit stayed at $6M. Why?

Shops earn $4.8M both years ($40M x 12%). Wholesale earned $1.2M ($10M x 12%) and still earns $1.2M ($20M x 6%) after doubling. Total profit: $4.8M + $1.2M = $6.0M both years, so margin falls from 12.0% to 10.0% (6 / 60). The lesson is the same as Ashgrove: growth in a lower-margin segment can cancel out, so ask for margin by segment before you celebrate or worry about the total. Pricing wholesale, rather than cutting it, is the first fix to test.

Where can you find more profitability case study examples?

Use this order. Start with a case where one driver explains the drop, as in Ashgrove. Then move to cases where price and cost move together, such as revenue decline or cost reduction prompts. Then try customer profitability, where the segment is the whole question. When a case asks whether a business breaks even, the break-even analysis guide covers that math.

For worked solutions across all case types, see case interview examples and the case interview frameworks guide. Firm-style practice sets are at McKinsey practice cases, and a retail version of a margin case is in the FreshCart retail profitability case page.