Barrons AP Environmental Science

Immigration refers to the number of individuals that enter the population,
while emigration refers to the number of individuals that leave the population.
Population change can be calculated using the following formula: Population
change = (crude birth rate + immigration) – (crude death rate + emigration)
EXAMPLE

In 1950, the population of a small suburb in Los Angeles, California, was
20,000. The birth rate was measured at 25 per 1,000 population per year, while
the death rate was measured at 7 per 1,000 population per year. Immigration was
measured at 600 per year, while emigration was measured at 200 per year. By
how much did the population increase (or decrease) in that year?

Answer:

The Population grew from 20,000 to 20,760 in one year.
Population change over time can be calculated using the formula

N 1     =   (NO +   B   +   I)  –   (D  +   E)  where

N 1 = new population size

NO = original population size

B = number of births between NO and N 1

I = number of immigrants (arriving) between NO and N 1

D = number of deaths between NO and N 1

E = number of emigrants (leaving) between NO and N 1

EXAMPLE

A   small   city    in  Ohio    had a   population  of  1,000   in  1920.   Over    the next    10

years,  there   were    100 births, 50  deaths, 200 people  who left    the city,   and 600

people  who arrived.    What    was the population  of  this    city    in  1930?

Answer: