CaseStar field guide · McKinsey Solve
Understand the task.
Then practise the decisions.
A practical guide to Solve-style preparation: what the official sources say, how our practice tasks work, and how to learn from a run.
Start with what is actually confirmed.
McKinsey describes Solve as a gamified problem-solving assessment and says preparation is not necessary. Its public material does not provide a complete specification for the named practice modules below. Read McKinsey’s introduction.
Official information
The invitation gives your assessment length. Each task has an untimed tutorial. Solve contributes to the application decision alongside other information. Official FAQ.
Candidate-reported formats
Names such as Red Rock, Sea Wolf and Sustainable Future Lab help organise preparation. Reports can differ between candidates. Do not treat reported timing or order as a universal specification.
CaseStar practice
Our scenarios, timings, worked examples and feedback are our own. They are designed for skill practice and format familiarity. They do not reproduce private assessment questions or predict an offer.
Choose the skill you want to practise.
Each link opens a brief, not a running timer. Use the tutorial first if the controls are unfamiliar. The durations below describe CaseStar.
Evidence → calculation → report
Red Rock
Start with the question. Find the records that answer it, calculate with consistent units, then report the result. Full practice includes the study and mini-cases.
8-minute free sample · 35-minute full practice
Open Red Rock brief →
Profile → select → treat
Sea Wolf
Read the site requirements. Compare microbes, check the treatment’s attribute averages and inspect its traits before committing your three-microbe team.
10-minute free site · 30-minute full practice
Open Sea Wolf brief →
Prioritise → decide → adapt
Sustainable Future Lab
Rank priorities and make decisions as evidence changes. Earlier choices affect later situations. Candidate-reported format; not a named module on the official Solve page.
About 6 minutes free · 20-minute full practice
Open Sustainable Future Lab brief →Ready for a longer sitting? The full mock offers CaseStar’s 65- or 85-minute practice sequence. Full-run access and current pricing are separate from these free samples.
Learn the move, not an answer key.
These small examples are original teaching exercises. Try each question before opening the explanation; none comes from the real assessment.
01 · Red Rock reasoning
Choose the right denominator.
A field report records 120 observations in the first period and 150 in the second. What is the percentage increase?
Reveal the calculation and the common mistake
The change is 30. Divide by the starting value: 30 ÷ 120 = 25%. Dividing by 150 gives 20%, which answers a different question. Before calculating, write the quantity, comparison period and unit you need.
Transfer to practice: collect the starting and ending values with their labels. Extra numbers do not improve this answer.
02 · Sea Wolf reasoning
Evaluate the treatment, not one microbe.
In this simplified practice rule, the team average must be between 5 and 7. Three microbes have values 4, 6 and 8. Does the team meet that one numerical requirement?
Reveal the treatment check
Yes: (4 + 6 + 8) ÷ 3 = 6. Two individual values sit outside the range, but the average is inside it. That does not establish that the whole treatment works: check every other required attribute and trait separately.
Transfer to practice: evaluate the complete team against the complete site brief before confirming it.
03 · SFL reasoning
Changing your mind can be consistent.
You planned fieldwork for Friday. A new access notice says that area is closed, while desk analysis can continue. What should change?
Reveal a defensible response
Move the blocked fieldwork, continue the independent desk work and update the affected stakeholders. Keeping the original schedule would ignore a changed constraint. Consistent judgement means applying the same decision principles to the new facts—not repeating the same action.
Transfer to practice: distinguish a dependency from a preference and identify exactly which evidence changed.
Try the selection mechanics.
This standalone micro-exercise shows feedback as you select. It uses CaseStar’s practice rules and does not start a full simulator run.
The interactive exercise needs JavaScript. You can still read the examples above or open the Sea Wolf practice brief.
A useful practice loop.
- Learn: finish the tutorial without a clock. Explain the rules back in your own words.
- Try: complete one sample. Notice whether the difficulty is reading, arithmetic, constraints or time management.
- Review: pick one concrete error. Write the evidence you missed and what you will do differently.
- Repeat: use a different scenario. Progress means applying the rule independently, not remembering the previous answer.
Use the practice loop above. The optional date planner becomes available when JavaScript loads.
Before the real assessment.
Close CaseStar and other preparation resources before starting. McKinsey’s integrity rules prohibit outside tools and assistance, including AI and pre-prepared notes, except for approved accommodations. Do not record or screenshot the assessment. Check the current rules.
Use the PC or Mac and technical check described in the official FAQ. If a technical issue occurs, contact the official support team at the time it happens. Direct non-technical questions and accommodation requests to your recruiter. Equipment and support details.
Questions worth settling before you start.
How long is McKinsey Solve?
Use the duration in your invitation. McKinsey’s FAQ says the email specifies your assessment length and that each task begins with an untimed tutorial. CaseStar’s 35-minute Red Rock, 30-minute Sea Wolf and 20-minute SFL formats are practice timings, not a way to infer your actual assessment from its total length.
Do I need to pay to prepare for Solve?
No. McKinsey says preparation is not required. If you want format familiarity, CaseStar offers free tutorials and short samples: 8 minutes for Red Rock, 10 minutes for Sea Wolf and approximately 6 minutes for SFL. Full-run access is checked separately; see pricing for current terms.
What score do I need to pass?
We do not have a verified public passing threshold. McKinsey says Solve is considered alongside the rest of your application and other assessments. CaseStar scores diagnose your practice; they are not an official percentile, pass mark or hiring prediction.
Is Sustainable Future Lab officially confirmed?
McKinsey’s public Solve page does not name Sustainable Future Lab. The CaseStar format is inspired by candidate reports and uses original branching scenarios. Neither a preparation website nor a longer invitation proves that you will receive this task.
Can I use this guide or AI during the real assessment?
No. Use this material before the assessment. McKinsey prohibits outside applications, websites, AI tools, pre-prepared notes and recording or screenshots during Solve, except for an accommodation approved in writing. Follow the rules in your invitation.
Sources and limits.
- McKinsey: Solve assessment overview and integrity rules.
- McKinsey: Solve FAQs, linked from the official page.
- CaseStar’s current simulator briefs and practice engine support the product descriptions and worked examples on this page.
Reviewed on 6 September 2026. We do not claim a universal module order, a published pass mark, a fixed retake window or a guaranteed result. Your invitation and recruiter take precedence.