Schedule mock interviews on the Meeting Board, join the latest community discussions in our Consulting Q&A and find like-minded Interview Partners to connect and practice with!
Back to overview

Determining the population in each age category?

Hey all, Does this way makes sense to determine the number of people in each catagory? 

For example, If the life expectancy in a country is 80 years and the population of the country is 50 million then, 

80 / 50 = 0,625 people in each year catagory. 

Lets say that I want to know the population segment from 0 to 16 years old. Then 

0,625 x 17 = Around 10,6 M people. 

Does this makes sense? 

What other possible way can we use to determine lets say the population segment from 0 to 16? 

Thanks 

3
4.7k
28
Be the first to answer!
Nobody has responded to this question yet.
Top answer
Deleted user
on Jun 02, 2018

Albeit incorrect - # of people for each age group tends to follow a bell shaped curve - this is a generally accepted way to calculate # of people for each age group.

if you want to be slightly more refine you can say that there are broadly 3 age groups: 0-20,20-60,60-80 and that the middle group should be weighted double for each year it has within it. So you would have that people for each year of age between ages 0-20 and 60-80 is 50M/(20+40*2+20)=0.42M and instead for each year of age between ages 20-60 is 0.42*2=0.84M

hope this helps,

andrea

4
on Jun 02, 2018
#1 Coach for Sessions (4.500+) | 1.500+ 5-Star Reviews | Proven Success: ➡ interviewoffers.com | Ex BCG | 10Y+ Coaching

Hi Anonymous,

it’s totally fine to use the approach you presented. As mentioned by Andrea, such computation is clearly an estimate, but it is good enough for market sizing, where you actually suppose to use estimates.

As an additional tip, unless you have specific strict constraints on the different age groups (eg 0-18 as a way to consider people who cannot have a driving licence) it is easier to approximate groups as 15 or 20 years– this will just make faster the computation starting from the initial population.

Best,

Francesco

Vlad
Coach
on Jun 02, 2018
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School

Hi,

You can either determine the number of people in each category or you can use a % share of each category:

i.e. if you need the population of 10-20, it is 10% of 50M or 5M. It makes sense to predetermine the age groups that you will use in the market sizing questions so that you pick the easy number from the beginning.

Best

Similar Questions
Consulting
Is final round only harder because of the partners being interviewer ?
on Jun 02, 2025
Global
9
400+
Top answer by
1st session -50% | Ex-McKinsey, Ex-Coca-Cola Strategy |Offical McKinsey Case Coach | +250 coaching sessions
21
9 Answers
400+ Views
+6
Consulting
Bain vs McK vs BCG: Which has more difficult maths ?
on Jun 08, 2025
Global
9
300+
Top answer by
Evelina
Coach
EY-Parthenon (6 years) l BCG offer holder l 97% success rate l 30% off first session l free 15' intro call l LBS
18
9 Answers
300+ Views
+6
Consulting
What do they look in a candidate?
on Aug 24, 2024
Global
5
1.8k
Top answer by
Hagen
Coach
#1 recommended coach | >95% success rate | 8+ years consulting, 8+ years coaching and 7+ years interviewing experience
65
5 Answers
1.8k Views
+2