Learn to solve the problem in front of you
A case interview asks you to make progress on an unfamiliar business question while someone observes your reasoning. You need to clarify the objective, decide what to investigate, work with information and explain a recommendation that follows from the evidence.
Quick Prep’s Case Interview Mastery brings those skills together through case explanations, worked examples and a repeatable practice method. The focus is useful for candidates who are starting their preparation and for those who have completed many cases but still struggle to move from analysis to a decision.
BCG’s candidate guidance emphasises structured reasoning, thoughtful questions, calculations and clear communication. These are broad skills to practise; the precise format should come from the employer’s instructions for your role. BCG: Case interview preparation
Clarify the decision and build a tailored structure
Begin by restating what the client wants to decide. Establish the metric, timeframe and constraints. “Improve performance” could mean raising profit, increasing market share, reducing waiting times or protecting cash. Each objective leads to a different analysis.
Then build an issue tree that explains how you will reach an answer. For a profitability problem, revenue and cost may be a useful starting point. For market entry, demand, competitive position, economics and execution may be more relevant. Explain the branches in the client’s context.
A structure is a working plan. It should make clear what information you need and why it matters. If new evidence changes the problem, update the plan. Continuing through irrelevant branches simply because you wrote them down weakens the discussion.
Turn hypotheses into useful questions
A hypothesis is a provisional explanation you can test. If a manufacturer’s margin is falling, you might investigate whether product mix has shifted toward lower-contribution items. Ask for information that would support or reject that explanation.
Prioritise questions by their potential effect on the decision. A detailed breakdown of office supplies is unlikely to matter if the case shows a large decline in selling price. Conversely, a small operating bottleneck can matter greatly when it prevents high-value sales.
When an exhibit arrives, read the title, time period, units, segment definitions and footnotes. State the important pattern and connect it to the objective. A chart description becomes analysis when you explain what it suggests and what to test next.
Calculate in a way another person can follow
Set up the equation before inserting numbers. Label units, estimate the expected range and check whether the result is plausible. Explain the implication after calculating.
Useful building blocks include contribution, break-even volume, percentage changes, weighted averages, market sizing, capacity and simple investment screening. More elaborate modelling should serve the case question rather than become an end in itself.
If you make an error, identify it and correct the calculation plainly. Recovery shows that you can monitor your work. Quietly carrying an implausible result into the recommendation makes the error more consequential.
Worked exercise: a price increase with volume risk
Illustrative interview exercise. All figures are fictional.
A business sells 100,000 units at 50 each. Variable cost is 30 per unit and annual fixed costs are 1 million. Current profit is:
100,000 × (50 − 30) − 1,000,000 = 1,000,000.
Management proposes a 10% price increase and expects unit volume to fall 8%. With price at 55 and volume at 92,000, profit becomes:
92,000 × (55 − 30) − 1,000,000 = 1,300,000.
The forecast implies a 30% profit improvement. To preserve the original 1 million profit, the business needs (1,000,000 + 1,000,000) ÷ 25 = 80,000 units. Under the model’s unchanged cost assumptions, it can tolerate up to a 20% volume decline before profit falls below the baseline.
The calculation supports further consideration of the increase, but the recommendation depends on evidence for customer response. Ask whether competitors can undercut the offer, whether contracts permit the change and whether the expected decline differs by customer segment.
A useful conclusion would recommend a measured implementation if demand evidence supports the forecast, identify the volume threshold and monitor contribution by segment.
Practise the full conversation
Case preparation should include opening, structuring, analysis, interpretation, brainstorming and synthesis. Isolated drills help a weak skill; full cases reveal whether you can use the skills together.
After each attempt, record one or two consequential issues. For example: the opening missed the timeframe; the revenue model confused users and paying accounts; the recommendation lacked a clear action. Repeat a small drill to address the issue, then test the improvement in a different case.
A practice partner can ask follow-up questions and challenge assumptions. Self-study can still be active: attempt the problem before reading the solution, explain the reasoning aloud and compare alternative approaches. Treat worked solutions as examples of defensible reasoning, not scripts to memorise.
Build recommendations from evidence
A clear conclusion states the action, the main supporting reasons, the principal risk and the next step. Quantify the effect where the case supports it. If the evidence is incomplete, make the recommendation conditional and identify the information that would change it.
Use the case interview resources and case studies for practice. Add Technical Skills Enhancement for calculation and exhibit drills, or an industry primer to practise adapting your reasoning to a different business model. Contact Quick Prep to discuss your current preparation priorities. If you want that practice structured and reviewed rather than self-directed, compare the preparation plans.