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Do you get extra "points" for getting an answer quickly in a market sizing/guestimate question?

Anonymous A

For example: How many petrol stations are there in the UK?

Surely the quickest way is:

1) Make an assumption of how many stations serve your home city's population (say 10 for 300,000 people)

2) That means 1 station serves around 30,000 people.

3) Get the total population of the UK approx. 60m, divide by 30,000 = 2000

4) Then adjust for areas with more service stations London, Birmingham etc

Vlad replied on 09/14/2018
McKinsey / Accenture / Got all BIG3 offers / More than 300 real MBB cases / Harvard Business School


Depends on how you got the market sizing question. There are 2 options:

  1. Market sizing in the middle of the case. Here you really need to calculate something really quickly. However, the way you've done it in the example is too quick and you'll get no additional points for this. Although it won't be a negative score. The interview may just ask you for other ways to do it.
  2. Market sizing as a standalone case / market sizing right at the beginning of the case. In that case, you'll score negative points, since your solution is probably too fast. However, you can mention that there are two approaches and you can use them to triangulate your answer. Knowing several ways to do the market sizing can definitely add the points.



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