children born 7 years ago

Question

Hi, I'm not sure to understand why you calculate #of children born 7 years ago using the 4% growth rate ?
If we assume an equal distribution of population per age, can't we say that the number of babies born/year (4.67M) equals the # of children of 7 years old ?

Answer 1

Hi there,

I would be happy to provide the solution:

In case there was no growth in total population, your assumption would right.
However, given the 4% growth rate, you first need to understand what total population and thus total children born 7 years ago was.

Best,

Hagen

Answer 2

You're right in terms of how to calculate the static number of people in each age cohort (assuming normal distribution across all ages).

However, in this particular exercise, you are also asked about the growth rate (4%), which means that you need to take this into account as well.

Needless to say, this initial assumption that all age cohorts are equal is purely a simplification since, in reality, there are booms in births every few decades that influence the distribution.

Best,
Cristian

Answer 3

Hi there,

Hagen is exactly right. This is testing your knowledge of growth rate. Which, inherently means that the # chances each year.