How would you estimate the percentage of the world's population in the northern hemisphere?

Case Interview market size Oliver Wyman
New answer on Oct 26, 2020
4 Answers
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James asked on Oct 24, 2020
Current Big 4 Consultant, preparing for upcoming interviews in November

I was asked the above question in one of my case interviews and am still uncertain how this would be market sized? Please could someone provide their thoughts on how they would approach this question...

(It turns out the answer was roughly 90, which quite shocked me due to my limited geography knowledge)

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Henning
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updated an answer on Oct 25, 2020
Bain | passed >15 MBB interviews as a candidate

I agree with Ian's approach. But here's a short cut: Take the total population (i think between7 and 8B, let's say 7.5B and subtract the countries on the south - much faster than trying ot estimate size of the countries on the northern HS.

And keep in mind, that Indonesia (certnainly among the top 10 largest populations) is mostly on the southern HS.

(edited)

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Clara
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Content Creator
replied on Oct 26, 2020
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut

Hello!

It depends a bit on the timing you are given to solve it.

If you have quite some time, I would go with countries, but in a normal interview, continents should be enaugh.

Split continent into hemispheres, particularly given attention to the super-populated ones (e.g., China, India), who are the ones that move the needle.

Hope it helps,

Clara

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Anonymous on Oct 26, 2020

I'd be very surprised if hemispheres segmented by continents is accepted as a reasonable response. That doesn't show much of structured thinking.

Ian
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updated an answer on Oct 24, 2020
#1 BCG coach | MBB | Tier 2 | Digital, Tech, Platinion | 100% personal success rate (8/8) | 95% candidate success rate

Hey Justin,

80/20 rule here. A few approaches to this.

1) Take the 10 largest countries you know and think about what % are above vs. below. You should basically only have Brazil below the equator, so 90%

2) Take the continents. I.e. 100% of North/Central America = North, 100% of Europe = North, 100% of ME = North, 100% of Asia - north, 100% of

S America = South, 30% of Afria = South

Then, because you know the populations of all the continents (you should), you can multiply it out!

(edited)

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Anonymous replied on Oct 26, 2020

Hello

I'd build on some of the answers provided below. Think about why does any interviewer ask this question. They are testing your general knowledge and your ability to develop a structured response to a highly ambiguous question.

1) What is the world's current population? About 7.7 billion and ask if you can round it up to 8 billion people.

2) The hemispheres are separated by the equator which passes through Ecuador in South America splitting the Americas, through (almost) middle of Africa and through the Indian Ocean. That means majority of South America, slightly less than half of Africa, parts of Asia (Indonesia, PNG, a few islands etc), Australia and NZ are the Southern Hemisphere.

4) Now try to assign South Hemipshere a % of the 8 billion. Explain the reason you've chosen this route is the 'elimination' technique rather than a bottoms-up technique of building the Nothern Hemisphere calculation. You could try estimating this population or ask if you can use an average of population per country based on 8 billion divided by 180 countries. I'd personally like to see the former. A great way to approach this would be AUS + NZ + Indonesia + Brazil is almost USA + Mexico + Canada, so ~500 million. So now you have estimated the 'Elephants' of the Southern Hemisphere.

5) Ask what data points can be used now for remainder of South America and for the bottom half of Africa. You can say based on your understanding of the geography the land size and density is similar to it should be at least another 500 million, to a total of 1 billion.

6) 1 billion / 8 billion = ~12%. So 88% lives in Northern Hemisphere.

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Henning gave the best answer

Henning

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