Calculating Population Changes – Answer Key
Most countries conduct a census of their population every few years to calculate the changes that have taken place in order to plan ahead for future needs of the changing demographics of their nations. Canada does this every five years.
A country’s population will change due to four main factors:
1.) Births 2.) Deaths 3.) Immigration 4.) Emigration
Two factors lead to increases in population:
Two factors lead to decreases in population:
Births and Immigration
Deaths and Emigration
In order to compare demographic trends from one country to another, rates (# of people per 1000 of the total population per nation) are used for a more accurate and relative comparison.
To change a whole number into a rate do the following:
Whole Number x 1000 = Rate per 1000 people
Total Population
Example: Convert the following for Canada:
Starting Total Population = 27 500 000
1.) # of Births: 412 500 x 1000
27 500 000
= 15 per 1000
2.) # of Deaths: 192 500 x 1000
27 500 000
= 7 per 1000
3.) # of Immigrants: 220 500 x 1000 4.) # of Emigrants: 41 259 x 1000
27 500 000 27 500 000
= 8 per 1000 = 1.5 per 1000
5.) Calculate the Natural Increase Rate (B.R. – D.R.)
15 – 7
= 8 per 1000
6.) Calculate the Net Migration Rate (I.R. – E.R.)
8
– 1.5
= 6.5 per 1000
7.) Calculate the Population Growth Rate (N.I.R. + N.M.R.)
(15 – 7) + (8 – 1.5)
= 8 + 6.5
= 14. 5 per 1000
8 .) Calculate the Population Growth Percentage (P.G.R. ÷ 1000 X 100)
14.5 x 100 = 1.5%
1000
Using the Population Growth Rate Percentage, we can use the Rule of 70 to calculate the Doubling
Time for a nation’s population if the population growth percent were to remain constant.
9 .) Calculate Doubling time (70 ÷ G.R.P). Round to one decimal place.
70 = 46.6 years
1.45%

10.) If asked to calculate the population at the end of the year after changes have been accounted for, simply subtract the decreases in the population from the increases in the population and apply to starting population number.
For example: Starting Population = 27 500 000
Formula: Increases
– Decreases applied to starting population
(Decreases + Emigrants) So, Increases = (Births + Immigrants)
= (412 500 + 220 500)
-
- (192 500 + 41 259)
= 633 000 - 233 759
= 399 241
This change is a positive number so it is added to starting population (if it was a negative number then there would be a decrease in the population so it would be subtracted from the starting population).
Therefore, 27 500 000 + 399 241 = 27 899 241
The new population at the end of the year is 27 899 241
*OR: You can change the growth rate into a whole number and apply it to the starting population.
For Example: The Growth Rate is 14.5 per 1000
This then becomes: 14.5 x 27 500 000 = 398 750
1000
Since this number is a positive one, it means that the population overall has increased by that amount so:
27 500 000 + 398 750 = 27 898 750
Therefore, The new population is 27 898 750*
* There is a slight difference between the two results because one uses whole numbers
(more accurate) while another is converting a decimal figure. Both are correct, but one is more accurate.
Use whichever calculation is the easiest for you to calculate correctly!