Below you find the three most common ones.
A brainteaser is the umbrella term for a number of different, usually quite short questions that test your analytical capabilities in a case interview. Your goal is to grasp, structure, and creatively solve an odd question. Make sure you don’t act surprised when the interviewer asks you such things as “Why are manhole covers round?” – in this case, you should come up with a structured approach and multiple creative solutions, or, “How many tennis balls can you fit in a 747?” – in this case, you should come up with a strong analytical answer, demonstrating that you are able to break down the problem into multiple parts and coherently analyze the situation.
Larger firms of the top-tier very rarely employ these types of questions.
Market sizing in consulting interviews
One of the most frequent questions a consultant has to answer during a project is to size the potential of a particular market. That is why these types of questions are often used in case interviews to grill applicants. Such questions can be part of a longer business case or sometimes asked as a standalone question. Typical questions include “What is the size of the dairy market in China?” or “How many diapers can we sell in Germany each year?” Sometimes interviewers will ask variations of this question such as “How many doors are in the city of Los Angeles?”
The key is to identify the main drivers of the number you are trying to estimate. Once established these with the interviewer in a structured manner, it is time to make assumptions for each driver and back them up with credible thinking. Lastly, use your tree of assumptions and drivers to calculate the final number. Be aware that the process and time you took is more important than the correctness of the answer (it should be in the same ballpark though). It is okay to use simple numbers for the sake of the calculations, so always round!
Business case (McKinsey: Problem Solving Interview)
Business cases are the most common and also the most difficult questions you can encounter in a case interview. Most top-tier firms solely employ business cases in their selection process. You will be asked to solve a typical business problem of a fictitious client. During the interview, you need to grasp quickly what is going on and what you are solving for. In order to do this properly, you need to split the problem into its components, ask the right questions to work your way through the case, analyze the facts given to you (at least partially the interviewers will let you calculate something), and eventually draw proper conclusions.
Typical business cases include questions around (not exhaustive):
- Market entry
- Profitability (growing revenue and reducing cost)
- Product introduction
- Competitive response
- Changes in the market
- Growth strategies
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