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Timing for math portion of case

case math case structure Case Timing Math problem quant problems Quantitative skills Structure timing
New answer on Mar 31, 2024
5 Answers
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Anonymous A asked on Jan 28, 2024

Hi everyone! 

Couple of questions: 

- What is considered an average time to set up the initial structure of the math portion of a typical case (including or excluding the time to check exhibits/discuss with interviewer)?

- What would be the average run-down time to walk the interviewer through the calculations? This obviously depends on the question but would be helpful to know to which extent I need to speed up my explanations + calculations

Thanks a lot

(edited)

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Cristian
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Content Creator
replied on Jan 29, 2024
#1 rated MBB & McKinsey Coach

You're not going to like the answer :) There is no set time. 

The interview is a conversation. What matters is not going at a certain speed through it. There is nothing that needs to be ‘finished’. You don't need to ‘crack’ the case or ‘close’ it. Most interviews nowadays don't even require a final recommendation. 

So you should take as much time as you need in order to provide a structured, clear answer. Think as if you would like to explain that calculation problem to somebody you are tutoring, or to a client. 

Just so you have an anchoring number, taking 1 minute is about average. But do bear in mind that depending on the complexity of the question, your skill level, your spikes, and the level at which you are interviewing, it could be more or less than that. 

Best,
Cristian

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Brad
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replied on Jan 28, 2024
Expert coach | Head of recruiting for Bain | 8+ years interviewing | Free intro call

Hi there,

 

Both good questions.

 

My view is that, although it changes by case, most folks structure their approach in 5-7 mins (inc. clarification questions etc). But frankly it doesn’t matter. I’d advise you to spend 10 mins, 12 mins, 30 mins (ok, maybe not 30 mins) structuring the case because this is where you actually solve it.

 

In my experience, most people do the bare minimum to try to advance through the case and get more info. Bad idea. For every minute you spend structuring and getting clearer on what could be going on you’ll save 5 mins on the analysis, and significantly improve your maths accuracy.

 

On your second question, you don’t need to run your interviewer through your calculations but you do need to make sure they’re following your approach. By way of illustration, I don’t see much value in saying “I multiplied 8 by 5 by 60%” but I do see a lot of value in saying “to calculate the average weekly billing time per person I multiplied a workday by 5 and assumed they were 60% utilised for billable activities”.

 

I encourage my students to use this approach to do 2 things: (i) bring the interviewer along the case with them and (ii) a structured layout of the logic (to themselves) they’re going to approach this math section. It’s amazing the number of times that you realise your approach isn’t quite right, you haven’t got all the numbers you need, you’re calculating weekly and not yearly numbers, etc.

 

Hope that helps.

 

Cheers,

B.

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Alberto
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replied on Jan 31, 2024
Ex-McKinsey Associate Partner | +15 years in consulting | +200 McKinsey 1st & 2nd round interviews

Hi there,

Don't obsess with a specific timeframe since every case is different. Make sure to practice enough to have a good rhythm to go over the data / charts, approach, calculations and conclusions.

Happy to keep talking about this in private, just send me a message.

Best,

Alberto

Check out my latest case based on a real MBB interview: Sierra Springs

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Ian
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replied on Jan 29, 2024
#1 BCG coach | MBB | Tier 2 | Digital, Tech, Platinion | 100% personal success rate (8/8) | 95% candidate success rate

Hi there,

- What is considered an average time to set up the initial structure of the math portion of a typical case (including or excluding the time to check exhibits/discuss with interviewer)?

A few minutes. You need to move through the math/charts/exhibits effectively/efficiently.

- What would be the average run-down time to walk the interviewer through the calculations? This obviously depends on the question but would be helpful to know to which extent I need to speed up my explanations + calculations

Under 1 minute. You need to be clear + concise with your communication.

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Pedro
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replied on Mar 31, 2024
Bain | Roland Berger | EY-Parthenon | Mentoring Approach | 30% off first 10 sessions in May| Market Sizing | DARDEN MBA
  1. Quality of the answer is the critical issue here, not speed.
  2. Almost always “being slow” is the result of having a confusing approach. It takes long because one is not doing it well (over-complicating, bad structure/approach to the estimation, etc.)
  3. What is reasonable depends on the complexity of the question itself. Calculating 5% of 200 million is not exactly the same as estimating the global number of medium duty trucks in the world.
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Cristian gave the best answer

Cristian

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