Short answer
Below is an original PST-style sample: a short client brief about a coffee roaster, one exhibit and three multiple-choice questions (profit per unit, a cannibalization calculation and the client's real objective), with worked answers. A strong candidate finishes it in about 7 minutes without a calculator. The PST is retired, but this format still trains Solve skills.
Key takeaways
- A PST-style case gives you a client brief, one or more exhibits and questions that each take one analytical step.
- Most points are lost on units, decimal places and answers that ignore the client's objective.
- A strong candidate solves this three-question set in about 7 minutes without a calculator.
- The McKinsey PST is retired; the skills in this sample transfer directly to Solve and to written cases at other firms.
How to use this sample
This is an original mini-set in the style of the McKinsey Problem Solving Test (PST): one client brief, one exhibit and three multiple-choice questions. Set a timer for 7 minutes, use only pen and paper, and answer all three before reading the solutions.
The PST is retired, and McKinsey now uses Solve, a gamified assessment. I still recommend this format for practice: it trains exhibit reading, calculator-free math and finding the client's real question, which Solve and case interviews both reward.
Candidates I coached usually underestimated four things: how much data each case contains, how hard the questions are, how fast two minutes per question goes, and how stressful it feels when the outcome matters. This set gives you a small, honest taste of all four.
The client brief
Harbor Coffee Roasters is a regional coffee roaster with three sales channels: wholesale to independent cafés, private-label coffee for supermarkets and a small online shop selling directly to consumers.
Revenue has been flat for three years. The CEO is considering a subscription service that ships fresh coffee to consumers every month. In a meeting with your team she says: "Supermarket buyers push our prices down every year, and last year two of our three largest café customers were bought by a national chain that roasts its own coffee. I want a channel where we own the relationship with the people drinking our coffee."
Exhibit 1: Harbor Coffee Roasters, sales by channel, 2025
| Channel | Volume (tonnes) | Revenue ($ thousands) | Gross margin |
|---|---|---|---|
| Cafés (wholesale) | 400 | 8,000 | 30% |
| Supermarkets (private label) | 600 | 7,200 | 20% |
| Online shop (direct) | 50 | 1,500 | 55% |
| Total | 1,050 | 16,700 |
Note: 1 tonne = 1,000 kg. Gross margin = gross profit as a share of revenue.
The questions
Question 1. Identify the channel that generates the highest gross profit per kilogram, and the amount.
- A. Cafés, $6.00 per kg
- B. Supermarkets, $2.40 per kg
- C. Online shop, $16.50 per kg
- D. Online shop, $1.65 per kg
Question 2. The subscription service is expected to raise online volume from 50 to 150 tonnes per year at the same price and margin per kilogram. The team estimates that 30 of the 100 additional tonnes will come from consumers who currently buy Harbor's private-label coffee in supermarkets. Calculate the increase in annual gross profit.
- A. $3,000 thousand
- B. $1,650 thousand
- C. $1,578 thousand
- D. $1,470 thousand
Question 3. Based on the CEO's statement, identify her primary objective for the subscription service.
- A. Increase the company's average gross margin percentage
- B. Reduce dependence on intermediaries who can squeeze prices or switch suppliers
- C. Increase total volume roasted
- D. Exit the supermarket channel within two years
Worked answers
Question 1: C (Online shop, $16.50 per kg)
Gross profit per kg = revenue x margin / volume.
- Cafés: $8,000k x 30% = $2,400k. Divided by 400,000 kg = $6.00 per kg.
- Supermarkets: $7,200k x 20% = $1,440k. Divided by 600,000 kg = $2.40 per kg.
- Online: $1,500k x 55% = $825k. Divided by 50,000 kg = $16.50 per kg.
Option D is the decimal trap: dividing $825k by 500,000 kg instead of 50,000 kg. A quick shortcut: online revenue per kg is $30, and 55% of $30 is $16.50. Target time: about 2 minutes.
Question 2: C ($1,578 thousand)
- Added online gross profit: 100,000 kg x $16.50 = $1,650k.
- Lost supermarket gross profit: 30,000 kg x $2.40 = $72k.
- Net increase: $1,650k minus $72k = $1,578k.
Option A uses revenue ($30 per kg) instead of gross profit. Option B ignores cannibalization. Option D subtracts café profit per kg ($6.00) instead of supermarket profit, so it uses the wrong channel. Target time: about 2.5 minutes.
Question 3: B
The CEO names two problems: supermarkets squeezing prices and café customers disappearing after an acquisition. Both are cases of an intermediary controlling her access to the end consumer. Her conclusion, owning the relationship with the people drinking the coffee, confirms that the objective is reducing that dependence.
Option A is a likely side effect, since the online margin is high, but she never mentions margin percentage. C is plausible for any growth initiative and has no support in her statement. D goes further than anything she said. Target time: about 1.5 minutes.
Stephan's note: Question 3 is the type I almost got wrong on my own PST, in a case about a fish restaurant. The tempting answer described the client's action, and the correct one described the reason behind it. Underline the sentence where the client explains their reasoning.
How did you do?
Add about one minute for reading the brief and exhibit, and the target total is about 7 minutes.
| Score | What it suggests | Next step |
|---|---|---|
| 3/3 in 7 minutes or less | Strong; ready for full timed sets | Take a full 26-question test |
| 3/3 but over 9 minutes | Accurate but slow | Drill exhibit reading and rounding |
| 2/3 | Typical first attempt | Review the error type: reading, math or objective |
| 0-1/3 | Foundations need work | Follow weeks 1-3 of the practice plan |
Where to go from here
One mini-set shows you the format; a full timed test shows you whether you can sustain it for an hour. The Key to the PST is a complete 26-question written-case test with multiple business cases and a full answer guide that explains every option. It was built for the PST, which is retired, and remains a realistic hour-long drill for the skills Solve rewards. See the Key to the PST page.
To structure your preparation, follow the 4-week written case practice plan. For technique, read how to beat a written case test, brush up with case interview math, and check the McKinsey test in 2026 for the current Solve format.
Frequently asked questions
Where can I find an official McKinsey PST sample?
McKinsey no longer publishes PST samples because the test is retired. Its careers site now offers Solve information and sample interview cases instead.
How long should each written case question take?
On the PST you had about 2 minutes 18 seconds per question, including reading. Aim for 90 seconds on reasoning questions and up to 3 minutes on calculations.
How many sample tests do I need before test day?
In my experience coaching candidates, two to three full practice tests were enough to feel confident, provided each one was reviewed carefully.
Are PST samples useful for McKinsey Solve?
Yes, for skill building. Candidate reports describe Solve's Redrock Study as a research, calculate and report task that uses the same reading and math habits.