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Lesson Note

Subject: Economics
Topic: Population

## POPULATION

Population is defined as the total number of people living within a country or a geographical areas at a particular time. Population, in other words, refers to the total number of children, adults (men and women), youth (boys and girls) living in a given geographical area, which may be a town, village or country, at a specific time.
The study of population is very important for many reasons. Such reasons include the determination of the working population, allocation of resources, the availability of labour, etc. As at 1982, the world population was put at 4.5 billion people. With the world average population growth rate at 1.8%, it is estimated that by the year 2000, the population of the world would have been 6.25 billion people.

## In terms of continents

Asia is the most populous continent in the world, followed by Europe, Africa, North America, South America, Australia and Antarctica.

## In terms of countries

China is the most populous country (1.39 billion), followed by Indian (1.32 billion), United States (329,877,505). In Africa, Nigeria is the most populous country with over 180 million people. These are population estimates for these countries by the year 2019.

## Population Census

Population census may be defined as the head count of all nationals of a country at a particular time. It refers to the counting by government of all the children, boys, girls, men and women, including the disabled, in a country at a given period of time.
Censuses are usually taken every 10 years. When a series of censuses has been undertaken properly, it becomes easier, using the rate of growth, to estimate the population between the periods of counts.
Population census provides information about age, sex, occupation, residence, etc. In Nigeria, several population censuses were taken by the government. The census of 1952/1953 was given a 31.12 million people. This figure, according to observers at that time, was underestimated.
Another census was conducted in 1962/63 which put the country’s population at 55.670 million. This figure, as of that time, was over inflated. This raised a lot of controversy regarding its reliability and acceptability.
In 1973, another count gave a population of 79 million people. This figure was rejected due to double counting and overestimation. In 1991, another population census, the most recent in the country, was taken. It was given as 88, 514, 501 people. Since then there has been no population census and the current estimate of Nigeria’s population as of 2019 is at 180 million people.

## Characteristics of a Good Population Census

i. It must be conducted by the government of the state or country where the census is taking place.
ii. It must be conducted at the same time (simultaneously) throughout the country.
iii. It must involve regular counting at specific intervals of time, e.g Nigeria’s population taken in 1953, 1963, 1973, etc, i.e at an interval of 10 years.
iv. It must reveal the population of a country at a specific period of time, e.g Nigeria’s population census at of 1973.
v. It must involve the physical counting of people rather than by proxy.
vi. It must involve experts who are knowledgeable in population studies and they must be of high integrity.

## Types of Population Census

There are two main types of population census. They are:
1. Defacto population census: This is the type of population census which involves the counting of only those who are present people physically during census. In this group, only those that are present people physically or seen are counted.
2. De jure population census: This is the type of population census which involves the counting of people who have been permanent residents of a specific area. It does not matter whether the person is present or not. This is the population census commonly referred to as counting by proxy.

## Importance or Reasons for Population Census

i. Population size: Population census helps the government to know the number of people living in the country and the structure of the population.
ii. Revenue estimates: It also helps in the determination of taxable adults so as to know the amount of revenue expected from that sector.
iii. Forecasts future economic needs: The population census also enables the country to forecast her future economic needs, e.g housing, food, etc.
iv. Determination of standard of living: Population census also assists in the determination of the standard of living of the people in a country through per capital income.
v. Determines the level of unemployment: Population census provides government with statistics to determine the level of unemployment in the country.
vi. Number of immigrants: The number of immigrants in a country can be known or estimated based on population.
vii. Provision of social amenities: Population census gives the government an idea of the different population in various parts of the country and this will help it in the provision of social amenities like housing, water, electricity, roads, schools, hospital, etc.
viii. Determination of population density: Population census helps the government to know areas in the country where population per land area is high or low.
ix. Allocation of parliamentary seats: Population is often used in Nigeria to allocate parliamentary seats. States with high population are given more parliamentary seats than states with low population.

## Problems Associated with Population Census

i. High level of illiteracy: As a result of the high level of Illiteracy in many developing countries, it has become very difficult to conduct a successful population census as these people do not give relevant and useful statistics. Information gathered from these sets of people are usually false and misleading.
ii. High cost: Huge amount of money is involved in the conduct of population census. Since most West African countries are poor, the resources required to conduct a successful census are not available.
iii. Political problem: Since population census is used in many countries to allocate resources to component states, population figures are usually falsified to enable some state gain more resources than others.
iv. Geographical barriers: Most communities are inaccessible due to mountains, valleys, rivers, etc. This makes population census difficult in these areas.
v. Lack of trained personnel: Trained personnel like demographers are not available hence the use of untrained personnel in the conduct of census lear to inaccurate results.
vi. Religious beliefs: The religious belief of some people is a major problem encountered during population census. Muslim women that are in purdah are not to be seen by men and this makes counting of such people difficult as they are counted by proxy.
vii. Lack of transportation: Most rural areas do not have motorable roads and this prevents or restricts enumerators from getting in touch with some communities.
viii. Lack of communication Facilities: Poor or total lack of communication facilities make population census very difficult, especially in rural areas.
ix. Poor regional planning: Most towns and villages are not planned. In most cases, the buildings are scattered, some without numbers. This makes it difficult for population officers to conduct a successful population census.

### Factors that can affect the size of a Country’s Population or Reasons for High Population Growth in West Africa

i. Increase in birth rate: Ij West African countries, there is increase in birth rate as it is the desire of every family to have many children.
ii. Decrease in death rate: There seem to be a reduction in the death rate. This generally may be due to more knowledge in modern medical services and this tends to increase population.
iii. Type of marriage: In West Africa, polygamous marriage is widespread. Here, a man marries between two to five wives. The number of children given birth to by these women will definitely increase the population.
iv. Religion: The type of religion practised by West African countries determines to a large extent the population of such countries. While Christianity does not support polygamy, the Islamic religion supports polygamy and this encourages rapid population.
v. Improved medical services: The availability of medical services has helped to reduce the rate of death hence population is sure to increase under this condition.
vi. Illiteracy: Majority of the people are illiterates and they do not know any medical way of controlling birth or family planning hence they continue to give birth and this increases the population.
vii. Poverty: A poor man believes in giving birth to many children. He has a strong conviction that one or more of his children will become wealthy and influential and this changes the status of the family.

i. Large labour: High population provides large labour force for the industries.
ii. Large market: High population is a source of large market for the goods produced by the industries.
iii. Defence: Organised army and other law enforcement agencies are easy to recruit in highly populated areas.
iv. Quick information dissemination: Because people stay everywhere in these areas, it is very easy for information to go around very quickly.
v. Attraction to investors: Investors are easily attracted to areas of high population because of large market for finished products.
vi. Urbanisation: Areas with large population do lead to urbanisation.

## Implication or Disadvantages of Large Population

The economic effect of a large population or high population density include:
i. Pressure on natural resources: Natural resources like fertile farmlands, minerals, etc become over exploited where there is high population growth in an area.
ii. Increase in crime wave: Areas of high population density are usually associated with high crime rate like armed robbery, car snatching, hired assassination etc. This may be due to lack of jobs, hence, people resort to crimes.
iii. Insufficient food: As a result of the high influx of people into an area, there will not be sufficient food to cater for the high population which leads to food shortage.
iv. Unemployment/Under employment: Areas of high population density usually do not have enough jobs for the ever increasing influx of people. This leads to unemployment and under-employment.
v. Inadequate housing: High population concentration leads to poor accommodation as the houses available may not be enough for the high population.
vi. Traffic congestion: Many people travel on the roads at the same time and this leads to traffic congestions most of the time.
vii. Environmental pollution: Poor housing, turn out of waste materialsfor due to high level of human activities generally lead to environmental pollution.
viii. High cost of living: As a result of high population density, it will result in a corresponding demand for goods and services and where these are not forthcoming in sufficient quantities, it will lead to high cost of purchasing them thereby leading to high cost of living.
Population Density
Population density is defined as the number of persons per square kilometre of land. The population of density of a country can be expressed mathematically as:
Population density = Total population / Land area
Example 1:
Calculate the population density of Nigeria, having a total population of 88,514,501 as of 1991 with a total land area of 923,768sq km.
Solution
Total population = 88,541,501
Total land area = 923,768sq km
Population density = Total population / Total land area
Population density = 88,541,501 / 923,768
Population density = 95.6 = 96 persons / sq km.
Population density may either be high or low depending on the number of people in a specified area or country. Generally, high population density occurs where there are many people in an area which leads to over population.
Similarly, a low population density refers to a situation where there are few people in a specified area of land.
Ageing or Declining Population
Ageing population is defined as a declining population with an increasing percentage of old people, while the relative percentage of children and workers are decreasing. Ageing or declining population is also known as a stationary or static population.

## Factors Responsible for Ageing Population

i. Decrease in birth rate: A fall or decrease in birth rate generally leads to declining population. This might be due to implementation of birth control and late marriages.
ii. Increase in death rate: A rise or increase in the death rate of the young ones through epidemics or poor medical facilities generally leads to a reduction in the number of people in the country.
iii. Emigration: The movement of young men or youth out of a country can also lead to declining population.
iv. War: The existence of war also lead to declining population as able-bodied youth are lost during war.
v. Disease: The outbreak of diseases can also lead to decrease in population as this reduces the number of young ones within the country.
vi. Natural Disasters: Natural disasters like flood, earthquakes, etc can lead to declining population, especially when the young ones are mostly affected.
vii. Poor medical facilities: Poor medical facilities generally lead to a decrease in population and when the young ones are the victims, ageing population is bound to set in.

i. Reduction in government expenditure: A declining population have fewer people to cater for and as a result there will be a reduction in expenditure by government.
ii. High standard of living: Standard of living has something to do with the number of people and available resources. With fewer people coupled with increasing resources, this will cause an increase in per capita income, which will result in higher standard of living.
iii. Reduction in congestion: As a result of decrease in the number of people, there will be a corresponding decree in congestion in terms of human, accommodation and vehicular traffic.
iv. Creation of job: As a result of increase in the number of old people, there will be creation of more employment opportunities for the few labour force.
v. Increase in savings: With decreasing population there is an increase in savings on the part of government.
vi. Increase in investment: As a result of the increase in savings, there will be enough capital for investment in important sectors of the economy.

## Implications or Disadvantages of Declining Population

i. Reduction in labour force: As a result of the decrease in the number of working class citizens or increase in the number of old people, there will be a reduction in the number of the labour force.
ii. Fall in gross domestic product: The fall in the size of the labour force would result in the fall in the productivity capacity of the country. The small labour force, combined with its liability to make optimum use of available resources, results in low savings and a fall in gross domestic product.
iii. Less mobility of Labour: As a result of the increasing number of old people, mobility of labour becomes difficult as old people may either stay at home or refuse to accept new ways of doing things.
iv. Risk of invasion: Due to the increase in the number of old people in a country, the risk of invasion by external forces is very high.
v. High dependency ratio: When the population of old people and the children are higher than that of the working class population, it will result in a high dependency ratio.
vi. Reduction in tax: As a result of the increase in the number of old people, who are not taxable, the tax expected from the few that are working will be reduced.
vii. Changes in pattern of demand: In a decreasing population, there will be a shift in demand in favour of goods and services used by old people.
viii. Lower reward for factors of production: There will be a fall in demand as a result of decrease in total demand for goods and services. Consequently, the amount of rewards associated with the factors of production will fall.

## Overpopulation

Overpopulation is defined as a situation where a country has more people than its physical and human resources can support with adequate living standards. In other words, overpopulation refers to a situation where the population exceeds the available resources of the country.
As a result of overpopulation people will compete for the available resources and due to the relative shortage of resources, there will be a general fall in standard of living of the people.

## Control of overpopulation

i. Family planning: People should go for family planning to enable them determine the number of children they can have and successfully cater for.
ii. Discouragement of early marriage: Early marriages which promotes high birth rate should be discouraged.
iii. Increase in food supply: This should be encouraged through mechanisation of agriculture, use of modern farming systems, fertilizers and improved seeds to boost agricultural production.
iv. Stiffening of immigration laws: This will make it difficult for people to migrate to areas already populated.
v. Sex and mass education: Mass education ought to be practised and sex education should also be taught to enlighten the people on the dangers of overpopulation.
Under-population
Under-population may be defined as the type of population that is less than the available resources of a country. It then means that the size of the population is so small that when combined with the available resources of a country and given the level of existing technology, it will secure minimum returns per head. In summary, under-population is a situation where the population is too small relative to the available resources. The standard of living of the area can be increased if the population is increased.

## Causes of under-population

i. A decrease in birth rate: A decrease in the birth rate in any country for whatever reason generally leads to under-population.
ii. An increase in death rate: An increase in death rate of the people in any country for whatever reason, be it war, diseases, old age, flood, famine, etc, also leads to under-population.
iii. High level of emigration: When the rate at which people leave a country (emigration) is higher than that at which people come in (immigration), under-population is bound to occur.
i. Abundant resources: There will be abundance of resources in areas where there are resources endowment.
ii. Availability of Employment: Due to the small size of the population and abundance of resources, employment opportunities will readily be available.
iii. Low pressure on social amenities: Owing to low population, there is also low pressure on social amenities in the area.
iv. Low congestion: Also, due to low population, there will be low or no congestion in housing, traffic etc.
v. Adequate planning: Owing to low population, these areas are properly planned for decent living.
i. Inadequate labour force: The available labour force is grossly inadequate to manage the abundant resources available in the state.
ii. Low level of production: As a result of low level of manpower available production is generally very low.
iii. Low savings and investment: Workers generally earn low as a result of low level of production income and this leads to low savings and investments.
iv. Low standard of living: Due to inadequate labour force that would have promoted output, the standard of living will eventually fall.
v. Small size of market: As a result of low level of income per capital and fewer number of people, the size of the market is usually very small due to low demand.

## Optimum Population

Optimum population may be defined as the type of population which when combined with the available resources and the given level of existing technology secure a maximum return per head.
Optimum production is neither too small nor too large. In other words, optimum population stands in-between the two other extremes of over population and under population. It is the best type of population and it differs from country to country and from time to time. Optimum population is dynamic hence it changes according to the changing quantity and quality of a country’s available resources. Optimum population in relation to overpopulation and under-population can be described by the diagram below.

## Implications of optimum Population

i. At a given level of technology, it balances population with available resources.
ii. The management or control of economy that has optimum population is very easy
iii. An optimum population ensures or secures a maximum return per head.
iv. An optimum population is the population that produces full employment.
v. Optimum population is a dynamic population that changes with the changing quantity and quality of a country’s available resources.

## MALTHUSIAN POPULATION THEORY

The MALTHUSIAN population theory is the outcome of an essay title “An Essay on population” written in 1798 by Reverend Thomas Robert Malthus, an Anglican clergyman and a well known political economist. The essay he wrote was influenced greatly by the rate at which the population in Europe at that time was growing at a very fast rate. In this essay, he highlighted the relationship between population and means of subsistence.
The main features of Malthusian theory
The man views or features of the Malthusian theory about population are:
i. That population was growing at a geometric progression such as 2,4,8,16,32 etc while food production or supply was growing at an arithmetical progression such as 1,2,3,4,5 etc.
ii. That there is a tendency for all living things to grow beyond the food available to them.
iii. That unless population increase is matched with means of subsistence, negative and positive checks will come into force.
iv. That the checks can be war, diseases, epidemics and famine.
v. That population is essentially limited by the means of subsistence.

## Developments Or Events That Have Proved Malthusian Theory Wrong

Developments or events that have rendered Malthusian theory wrong or irrelevant in present day situation is found in developed countries such as England, America, Japan, Germany etc. These developments include:

i. Development of technical knowledge and mechanisation: The development of technical knowledge and mechanisation of agriculture in advanced or developed countries has helped to increase food supply.
ii. Changes in social attitude: Changes in social attitude like family size and family planning or birth control in these countries.
iii. Efficient transportation system: Increased efficiency in the transportation system enables more materials to be provided to areas that needed them.
iv. Industrial revolution: The industrial revolution, especially in Europe, also changed the idea of land as a fixed factor of production.
v. Medical improvement: Medical Improvement by way of efficient health care services also enables people to enjoy long life thereby proving Malthus theory wrong.
vi. Interdependency of nations: The interdependency of nations for goods and services available in large quantities as a result of international trade.
Developments or events that have proved Malthusian theory right
Developments or events that have proved Malthusian theory right or valid in developing countries in Asia, Africa and even in the present day situation in Nigeria. The events are as follows:
i. Negative attitude: Negative attitude like practice of polygamy, giving birth to many children, etc have made the population of many developing countries, including Nigeria, to increase on daily basis.

ii. High population and low food population: The population of many developing countries is growing at a geometric progression while food production is growing at an arithmetical progression.
iii. Difficulties in eradicating poverty: Poverty, which is inherent in a given society according to Malthus, has proved extremely difficult to be wiped out of many poor countries.
iv. Poor economic development: Rapid population growth militates against rapid economic development and it grows faster than per capital income.
v. Fallen standard of living: The standard of living of many developing countries has fallen as a result of increase in population.

## Demographic Transition Theory

The theory of demographic transition is the latest attempt made to provide a historical analysis into the population problems of developing countries. It tends to explain the reasons why all developed countries several years ago went through three identical stages of population history.
The demographic transition theory puts up a model which recognises three main stages in the process of population growth or demographic transition. The three stages are:

## Stage I: The Pre-industrialisation stage

The main feature of this stage is birth rate and high death rate. The population at this stage is either static or increasing or decreasing at a very low rate. The population transition remains fairly stable.

## Stage II: Transitional stage

This stage is characterised by high birth rate accompanied by low death rate. This stage leads to high population as a result of a number of factors such as industrialisation, urbanisation, better diet, higher income, improved medical services, etc. This stage marks the beginning of demographic transistion. Many developing countries are currently at this stage of population growth.

## Stage III: Post transitional stage

This stage is characterised by a low birth rate and low death rate. In other words, there is a relatively stable population with an older and larger population. This stage is associated with developed countries.

## Criticism Against Demographic Transition Theory

i. It is completely wrong to use the theory for general applications as it varies from one country to another.
ii. Crude birth rate widely used in the theory is not the only way to measure fertility.
iii. The main causes of decline in population may be different in different countries.
iv. It fails to predict the levels of birth rate and death rate.
Population Distribution or Structure
Population distribution refers to the ways in which the population of a given country is distributed into certain categories such as age, sex, occupation and geographical distribution.

## Age Distribution

Age distribution may be defined as the break down of the population of a country into age groups. Age distribution in economics is very important as it shows the usefulness of population and the supply of labour required in different sectors of the economy.
The population of a country can be divided into the following three age groups. These are:
i. 0 – 17 years
ii. 18 – 60 years
iii. 60 years and above.
From the above classification, the population within the age bracket 0 – 17 years includes the infants, children, pupils in nursery, Primary, Secondary and tertiary institutions. This age group is called dependent populatio because they are not economically productive as they cannot be employed in the labour market. They will need to depend on other groups, for their needs. If the Population of this age group is very high, it has lots of economic implications such as putting more pressure on the working class, low savings, provision of schools, and other children goods and services, etc.
The age group 18 – 60 years is popularly referred to as the active population or working population or labour force. This is the economic age bracket that are involved in productive activities hence they are also classified as dependent population.
In summary, the age distribution of any given population can be grouped as follows;
i. 0 – 17 years is children ( Dependent population)
ii. 18 – 60 years in adult (working population)
iii. 60 years and above (old age, dependent population)
The Advantages or Importance of Age Distribution of Population
i. Determination of tax: With the knowledge of age distribution of the population, the expected tax easily be determined based on the number of people in the working group or labour force.
ii. Knowledge of dependent: The number of the dependants ( 0 – 17 years and 60 years and above) can be determined easily through age distribution in a Population.
iii. Size of labour force: With a good age distribution, the number of people working can easily be determined.
iv. Determination of government budget: The age structure of a population will assist government to draw up its budget. If the example the population of the children ( 0 – 17 years) is very high, it means the government will need to vote a huge amount of money to provide goods and services required by this age group than for other groups.
v. Production pattern: The age distribution of the population will help the manufacturer to determine the pattern of production to meet the needs of a particular age group.
vi. It determines the nature of market: The understanding of the age structure of a population will help to determine the nature of market, e.g a population with high number of children will create more market for children goods and services.

## Economic Implications Or Effects Increase In The Population Of Dependants

The dependants are the population that are between 0 – 17 years, which include the infants, pupils in nursery, primary, secondary and those in tertiary Institutions, and the old age (over 60years) that are not working but depend on the working population (18 – 60 years) to cater for all their needs or requirements. If the population of the dependants is higher than that of the working class, it has the following economic implications.
i. High taxation: The working population will be made to pay higher amount of tax to take care of the dependants.
ii. Increase in prices: The prices of goods and services will rise as a result of an increase in demand by the dependant population.
iii. Low savings: When the proportion of the children and the aged (dependants) is large, less income is saved as more of the income is spent in catering for the dependants.
iv. Low investment: In a situation where the working class spends all they have to cater for the dependants, there will be little or nothing to save and when there are no savings, little or no investments are made.
v. Increase in imports: When the demands by children and the aged are not met, there will be an increase in the importation of children and the aged goods and services.
vi. Low supply of labour: Since the percentage of the working population is relatively low, it then suggests that there would be a relatively low supply of labour.

## Sex Distribution

The sex distribution refers to the classification of a given population according to sex or gender (i.e male and female). Sex distribution can easily be obtained from a population census of a given country which shows the total number of males and the total number of females.
A knowledge of the total number of males and females in a country will assist the government to make the necessary plans to cater for the population. If, for example, the population of the female is higher than that of the males, it means government will have to plan to provide goods and services for more people because such a country will give rise to high population.
Nature has, however, tried to balance the number of males with that of the female in such a way that the differences in number between the two is usually very small.

## Occupational Distribution

Occupational distribution of a population refers to the classification of the working population into different types of work they engage in. The occupational distribution in any population is influenced by a number of factors. These include:
i. The level of education
ii. Availability of natural resources
iii. The level of technology
iv. The types of production activities
The major types of production activities or industries are primary (extractive), manufacturing, construction, commercial, direct and indirect services. In West Africa, majority of the occupationally distributed population is found in farming, mining, fishing, lumbering etc.

## Geographical Distribution

Geographical distribution of a given population refers to the spread of people into separate geographical areas within a country. The distribution may be due to occupation, presence of mineral resources, historical factors, seat of government, availability of social amenities, etc.
In Nigeria for example, the population is not equally spread or distributed. Some areas are highly populated while others are poorly populated.

## Areas Of And Reasons For High Population Density In Nigeria

i. The Yoruba land of the South-West, which includes Lagos, Ibadan, Akure, Abeokuta, Ado-Ekiti, Oshogbo.
ii. The Hausa land of the North, which includes Kano, Kaduna, Jos, Sokoto.
iii. The Igbo land in the South-East, which includes Enugu, Onitsha, Owerru, Aba.
Reasons for high population density in these areas;
1. Favourable climate: The above areas have adequate rainfall, which ensures the production of food, especially in the West and the East, and is also favourable for human habitation.
2. Fertile soil: Fertile soil favours the cultivation of cocoa and kolanut in the West, Oil Palm, Yam and Cassava in the East, groundnut and cotton in the North.
3. Natural attachment/historical factors: The growth of some empires in the past like Kano and Oyo empires favours high population densities.
5. Employment Opportunities: The availability of jobs in these towns also increased the population.
6. Presence of minerals: The presence og minerals also contributed to high population densities of some towns, e.g coal in Enugu, crude oil in Port Harcourt, etc.
7. Presence of industries: The presence of industries in Lagos, Ibadan, Kano, etc provides jobs and cheap goods for the people.

## Areas Of And Reasons For Low Population Density In Nigeria

i. The Middle Belt of Nigeria comprises Kwara, Kogi, Benue, Niger and Abuja areas.
ii. The Nigerian Delta region, e.g Rivers, Bayelsa states.
iii. The extreme North East of Bornu and Yobe states.
Reasons for low Population Density in these areas include:
i. Relief: The presence of rugges highlands in some of these areas leads to low population.
ii. Poor drainage: The Middle Belt lies in the Niger-Benue valley and Niger-Delta areas which make settlement difficult because of the Niger-Benue rivers.
iii. Unfavourable climate: High temperatures and low rainfall, especially in Bornu and Yobe states encourage low population concentration.
iv. Poor soils: Areas like Bornu and Yobe have poor Sandy soils which do not support serious farming activities.
v. Historical factors: The trans-Sahara and trans-Atlantic slave trades aided the depopulation of the Middle Belt.
vi. Low economic activities: Lack of basic amenities, low commercial and industrial activities encourage low population in the Middle Belt of Nigeria.

## Example 1

The total number of males in a country which has a total land area of 140,000sq Km is 150,000,000 while that of the females is 130,000,000 including all migrants. Calculate
(a) The total population of the country
(b) The population density of the country
Solution
(a) Total population = No of males + No of females
= 150,000,000 + 130,000,000 = 280,000,000 People
(b) Population Density = Total Population / Land area
= 280,000,000 / 140,000 = 2,000 persons per sq Km.

## Example 2

If the population density of Tanko district is 3,500 persons per sq Km, and the total population is 1,400,000 people. Calculate the total land area of Tanko district.
Solution
Land area = Total Population / Population Density
Land area = 1,400,000 / 3, 500
Land area = 400 sq Km.
Some Population Formulae
Rate of population growth R = Birth rate – Death rate + Net migration
Net migration = Immigrants – Emigrants
I.e the difference between the number of immigrants and emigrants is Net migration.
Natural increase = Birth rate – Death rate
Percentage Increase = New Population – old Population. × 100
Old population
Dependency ratio = Dependent population / Working or independent population.
Example 3
Use the information table and answer the following questions

Calculate:
(a) The natural increase of the population in 1996
(b) Determine the net migration within the period.
(c) The rate of growth of the population in 1996
(d) The population of the country in 1996
(e) What is the percentage increase in the population of the country from 1980 to 1996
Solution
(a) Natural increase = Birth rate – Death rate
= 48 million – 12 million = 36 million
(b) Net migration = Immigrants – Emigrants
= 10 million – 4 million = 6 million
(c) Rate of population growth, R = Birth rate – Death rate + Net migration
= 48 million – 12 million + 6 million = 42 million

(d) Population of the country in 1996 = 1980 Population + Net migration + Birth rate – Death rate
= 56 million + 6 million + 48 million – 12 million = 98 million
(e) Percentage increase from 1980 to 1996
= New Population – old population. × 100
Old Population. 1
= 98 million – 56 million. × 100
56 million 1
= 42 million. × 100
56 million
= 0.75 × 100
= 75%
Example 4
The pie chart below represents the age of distribution of population. The total population is 240 million.

From the information above, Calculate:
(a) The population of children between 0 and 17 years
(b) The population of old people (60 + years)
(c) The dependency ratio
Solution
(a) Population of children between 0 and 17 years = 120 × 240
360. 1
= 28,800
360
= 80 million
N.B “the 360 is gotten by adding the percentage of each age in the pie chart, i.e 120% + 150% + 90% = 360 and the 240 used is the total population given in the question”.

(b) Population of old people (60 + years) = 90 × 240
360. 1
= 60 million
(c) working Population (18 – 59 years) = 150 × 240
360. 1
= 100 million
Dependency ratio = Population of children ( 0 – 17 years) + Population of old people (60+ years)
Working Population (18 – 59 years)
= 80 million + 60 million
100 million
= 140 million
100 million
= 1.4 / 1 or 1.4 : 1

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