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Should I anticipate these types of questions for an MBB online test?

Question:

There are 500 cars on a sales lot, all of which have either two doors or four doors.  There are 165 two-door cars on the lot.  There are 120 four-door cars that have a back-up camera.   Eighteen percent of all the cars with back-up cameras have standard transmission.  If 40% of all the cars with both back-up cameras and standard transmission are two-door cars, how many four-door cars have both back-up cameras and standard transmission?

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Top answer
Pedro
Coach
edited on Sep 01, 2025
30% discount in September | Experienced interviewer & consultant (+5 years) | ex-BCG | RWE

Hello,

Based on my experience, this type of "out-of-context" sizing questions have became out of fashion. Nevertheless, it is likely that you will be asked to do a sizing exercise related to a case (e.g., what is the size of x market segment?).

That said, the following steps (and skills tested) apply to both cases (some of the steps are not applicable in the case of online test - only interview):

0. Clarify the question: What are we sizing? where? when?

1. Choose the approach: Top-down vs. bottom-up - usually, strategy consultants think top-down (i.e., start from a broad perspective and then narrow it down)

2. Break the problem into small, logical pieces: e.g., Market size = total number of addressable customers x % adoption x average spend per customer

3. Make assumptions - and make them explicit: i.e., Consultants never have perfect info! With this exercise, firms are basically testing if you are the kind of person that does not get stuck and can progress in the right direction in moments of uncertainty)

4. Do the math accurately: it is better to take your time and do each step carefully than getting it wrong; try to sanity-check with figures you know from real life (e.g., GDP, industry sizes)

5. Communicate the answer in an executive manner: put the answer into the case context (seems trivial but I have seen candidates totally forget the case when doing this exercise); for extra points, communicate in ranges (e.g., 15-20M€) - you should be able to recognize that there is high uncertainty around the final answer as it is a broad estimate

Oussama
Coach
on Sep 01, 2025
Ex-Bain & Company consultant with Corporate strategy experience, and unique prep cases for consulting interviews

Hi there,

Yes this a typical question combining both logical and mathematical skills, so you can expect to have this type of question during the online test.

You can find other mock-up questions online, and I would recommend practising regularly, so that you get the gist of it. The questions can be different, but their essence and the pitfalls are fairly similar

Feel free to reach out to me if you wish some help to prepare for MBB interviews!

Best,

Oussama