How woudl you figure this out?

Question

was wondering how you would do a simple demography problem that doesn't have to be 100% accurate.

There are 58,133,509 people living in Italy. 54,064,163 are Italians and 4,069,346 ethnic minorities. The total fertility rate for the Italians is 1.15 children per woman in her lifetime. The total fertility rate for the ethnic minorities is 3.6 children born per woman. And each year there are 2.06 ethnic minority migrants per 1,000 of total population. The average life span for the Italians and the ethnic minorities is 79.81 years. The age structure for the population is as follows:

0-14 years 13.8%
15-65 years 66.5%
65 years+ 19.7%

Hopefully my information helped. Do you know how to figure out the precise year in which ethnic minorities will outnumber the Italians?

50% of the population is female in both groups.

Answer 1

Treat it as a flow problem. People flow in through birth rate and migration and flow out through death.

Call
I(t) the number of Italians vs time
E(t) the number of ethnic minorities vs time

You've given the start values: I(0) and E(0)

I assume that migration means net flow in. You've also implied that Italian migration is zero.

Need some symbols:

Im(t) = 0
Em(t) = 2.05*(E(t)/1000)

Births:
Ib(t) = 1.15* I(t)/2 ( the division by 2 to get women)
Eb(t) = 3.6*E(t)/2

Deaths:
this is tricky because you don't exactly know what average lifespan means....however, since they are the same for both groups, it represent a constant shift downward in the curves. I think that you can ignore it.

Hopefully this is a good start...

Answer 2

One would need to know how many women in each population group there are, since the fertility rate is not based on total population, but only on the female portion of the population, as well as the average age at which the women reproduce.

Also, the age ranges are too general, since some women will reproduce at 15 (a small minority) - some in their 20's, some not until their 30's, and a few in their 40's.

Furthermore, a portion of the population has already reproduced, and can no longer be counted as adding to the population.

There are too many unknown variables to solve the puzzle.

Answer 3

i have absolutely no idea! that is a toughy and will take me hours to work out...lol
sorry

rikku