 # Population Formulas – Compare Trends. An example… ► Let’s say a country has a population of 30,000,000.  Births = 390,000immigrants = 220,000  Deaths.

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Population Formulas – Compare Trends

An example… ► Let’s say a country has a population of 30,000,000.  Births = 390,000immigrants = 220,000  Deaths = 210,000emigrants = 60,000 ► How can we figure out how fast their population is growing???

► Birth Rate – the number of people born per year x 1000 population For example: BR = 390,000 x 1000 30,000,000 30,000,000 BR = 13 (this country had 13 people born per 1,000 people in that country)

► Death Rate – the number of deaths per year x 1000 population population For example: DR = 210,000 x 1000 30,000,000 30,000,000 DR = 7 (this country had 7 people die per 1,000 people in that country)

► Natural Increase Rate = birth rate – death rate Example: 13 – 7 = 6 (per 1000) This means that the natural increase rate for this country is 6 people per 1000

► Immigration Rate the number of immigrants per year x 1000 population population For example: IR = 220,000 x 1000 30,000,000 30,000,000 IR = 7 (this country had 7 people immigrate per 1,000 people in that country)

► Emigration Rate the number of emigrants per year x 1000 population population For example: ER = 60,000 x 1000 30,000,000 30,000,000 ER = 2 (this country had 2 people emigrate per 1,000 people in that country)

► Net Migration Rate = Immigration Rate – Emigration Rate Example: 7 – 2 = 5 (per 1000) This means that the net migration rate for this country is 5 people per 1000

► Population Growth Rate = Natural Increase Rate + Net Migration Rate Example: 6 + 5 = 11 (per 1000) This country is growing at a rate of 11 people per 1000.

► Always express the population growth rate as a percent!! 11 X 100 = 1.1 % 1000 1000 Or you can simply move the decimal one spot to the left.

► The Rule of 70 (Doubling Time) 70 70 Population Growth Rate (as a percent) Population Growth Rate (as a percent) 70 = 63.6 years 70 = 63.6 years 1.1 1.1 What this tells us is that the population of that country will double in 63.6 years.

► Example – The African country of Togo Togo has a population growth rate of 3.6% 70 = 19.4 years 70 = 19.4 years 3.6 3.6 The population of Togo will double in under 20 years.

Time to practice…. ► A country has a population of 1,807,242.  Births = 50,250immigrants = 13,605  Deaths = 42,658emigrants = 11,500 ► Do all the calculations (just like in the example we did)

Answers ► Birth rate = 27.8 per 1,000 ► Death rate = 23.6 per 1,000 ► Natural increase rate = 4.2 per 1,000 ► Immigration rate = 7.5 per 1,000 ► Emigration rate = 6.4 per 1,000 ► Net Migration rate = 1.1 ► Population Growth rate (%) = 5.3 = 0.53% ► Doubling Time = 132.1 years

Another practice question…. ► A country has a population of 726,000  Births = 12,500immigrants = 3,605  Deaths = 6,100emigrants = 1,500 ► Do all the calculations (just like in the example we did)

Answers ► Birth rate = 17.2 per 1,000 ► Death rate = 8.4 per 1,000 ► Natural increase rate = 8.8 per 1,000 ► Immigration rate = 5 per 1,000 ► Emigration rate = 2.1 per 1,000 ► Net Migration rate = 2.9 ► Population Growth rate (%) = 11.7 = 1.17% ► Doubling Time = 60 years

Homework question…. ► A country has a population of 8,000,000  Births = 200,000immigrants = 125,000  Deaths = 40,000emigrants = 30,000 ► Do all the calculations.

Homework Answers Homework Answers ► Birth rate = 25 per 1,000 ► Death rate = 7.3 per 1,000 ► Natural increase rate = 17.7 per 1,000 ► Immigration rate = 1.25 per 1,000 ► Emigration rate = 1.5 per 1,000 ► Net Migration rate = 0.25 ► Population Growth rate (%) = 17.0 = 1.7% ► Doubling Time = 41 years

The end….

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