Population Growth

Population change has two broad parts: natural increase, which is births minus deaths, and net migration, which is people entering minus people leaving. If births and deaths are nearly equal, natural increase may be close to zero. The city can still grow if net migration is strongly positive, meaning many more people arrive than depart.

Therefore option A is correct. The wording says growth is mainly driven by net migration, so it does not require births to be unusually high. Births can be approximately equal to deaths while incoming migrants add substantially to the city’s population. The other choices use absolute words such as “always” or incorrectly claim that births or the birth rate disappear.

Percentage increase compares the amount added with the original amount, not with the final amount. First subtract the initial population from the final population to find the absolute increase. Then divide that increase by the initial population and multiply by 100. Keeping the same units throughout avoids confusion between millions and individual people.

The increase is \(2.75-2.5=0.25\) million, or 250,000 people. The percentage increase is \((0.25/2.5)\times100=10\) percent. Equivalently, \(250000\div2500000\times100=10\) percent. Therefore, option C is correct. Using the final population as the denominator would calculate a different measure.

The Rule of 70 gives an approximate population doubling time by dividing 70 by the annual growth rate expressed as a percentage. It assumes that the rate remains roughly constant and gives an estimate rather than an exact prediction.

For a growth rate of 3 percent, the doubling time is \(70 \div 3 = 23.33\) years, approximately. Among the choices, 23 years is the closest value, so option B is correct. The answer is not 30 years because that would imply a lower growth rate. In real populations, changing birth rates, death rates, and migration can make the actual time different.

A large young population creates population momentum. Many young people will enter reproductive ages in the future, so the number of births may remain substantial even when the birth rate per person is falling. As a result, total population can continue to grow for some time. The eventual direction will also depend on how quickly fertility declines, mortality changes, and migration occurs.

Thus option B is the most appropriate: population may continue growing for some time. A falling birth rate does not cause an immediate population decline, especially when the age structure contains many young people. The population will not necessarily remain stable forever, and young people do have an important demographic effect. The statement is appropriately cautious because the exact duration cannot be determined from the information given.

Correct answer: B. Population change has two major components: natural increase and net migration. Natural increase equals births minus deaths. If deaths exceed births, natural increase is negative. However, people entering the country create positive net migration. If immigration is equal to the natural decrease, total population remains stable; if immigration is greater, total population grows. A is wrong because it ignores the effect of immigration. C is wrong because migration directly adds or removes people from the population. D is wrong because migration does not automatically make the birth rate rise; birth-rate changes depend on reproductive behaviour and other social conditions. For example, a natural decrease of 100,000 combined with immigration of 100,000 gives no total change, while immigration of 150,000 produces a net increase of 50,000. Memory cue: total change = births − deaths + net migration.

Migration can be measured in two ways. Gross migration counts movement in both directions, while net migration finds the difference between people entering and people leaving. Equal flows can therefore produce a zero net result without meaning that no movement occurred. This distinction is important when studying population change and mobility.

Here, 50,000 people enter and 50,000 leave. Net migration is \(50000-50000=0\), so migration alone does not change the population. Gross movement is \(50000+50000=100000\), showing that a large number of people moved. Therefore, option B is correct. It is incorrect to choose “no migration” because movement clearly occurred.

Total percentage growth is measured against the initial population. The population begins at 10 million and increases by 2 million over the ten-year period. The question asks for the total growth during that period, not the average annual growth rate. Therefore, divide the total addition by the starting population.

The calculation is \(\frac{2000000}{10000000}\times100=20\) percent. Equivalently, 2 million is one-fifth of 10 million, and one-fifth equals 20 percent. Hence option C is correct. If the question asked for an annual compound rate, a separate calculation would be needed; that is not what is requested here.

A total population increase of 20% over ten years tells us the relationship between the beginning and ending populations, but not the exact path between them. The final population is 120% of the initial population, and the absolute change is positive. However, growth may have been uneven: some years could have had higher growth and others lower growth.

Therefore, we cannot state with certainty that every year had exactly 2% growth. Also, even constant annual growth that produces a 20% total increase would generally involve compounding, not simply 20 divided by 10. Hence option C is correct. The question asks what cannot be concluded, and the exact yearly pattern is not supplied.

Per-person water availability is found by dividing the total available water by the number of people. If the total water supply remains constant while population increases, the denominator becomes larger. The same total amount must then be shared among more people, so the amount available to each person falls. This is a direct result of division, not automatic destruction of water.

Therefore, option A is correct. Population growth does not necessarily destroy water, and per-capita availability is directly related to total supply and population size. The statement that water supply automatically rises with population contradicts the condition that total supply is constant. The important change is that more people share the same resource.

When a city’s population grows but the number and capacity of schools stay unchanged, the existing schools may have to serve more children. If the number of school-age children also rises, more students may be placed in each school or classroom. This can increase pressure on rooms, teachers, furniture, and other facilities.

The exact impact depends on the age structure of the new population, so the result is described as likely rather than certain. Nevertheless, unchanged school capacity combined with population growth commonly increases demand and student pressure. Therefore, option A is the best answer. The other choices contradict this reasonable population-service relationship.

The working-age population forms the main group seeking or holding employment. If this group grows quickly but the number of jobs does not grow at a similar pace, more people will compete for each available job. Some people may not find work at all, while others may find only part-time, irregular, or low-productivity work. This situation can raise unemployment or underemployment.

Therefore option A is correct. It is not reasonable to assume that everyone's income will increase when job opportunities are limited. Birth rates do not automatically become zero, and population does not immediately decline simply because employment growth is slow. Other outcomes may also depend on education, migration, and policy, but the most direct likely result among the choices is increased unemployment or underemployment.

A growing working-age population can become an economic advantage when people receive good education, useful skills, health support, and suitable jobs. Employed workers can produce goods and services, earn income, pay taxes, and save money. These effects may raise economic output and support development. This possible benefit is often called a demographic dividend or demographic opportunity.

Therefore option A is correct: economic output may increase. The benefit is not automatic merely because the working-age group is large; education, skills, health, and employment are essential conditions. The other choices are unreasonable. Population cannot immediately become zero, a lower death rate is not inevitable, and resource demand does not disappear. A larger working-age group creates an opportunity, not a guaranteed result.

Birth rate affects the size of younger age groups. If fewer babies are born over a sustained period, later cohorts entering school age will generally be smaller. The effect does not appear immediately because babies need several years to reach school age. Therefore, the correct choice is A: after some time, the number of school-age children may decline.

This change may reduce demand for new schools, classrooms, or teachers, although existing demand can continue for some years because older children are already enrolled. The word “may” is appropriate because migration, mortality, and regional differences can alter the outcome. A declining birth rate does not immediately double school demand, and it clearly has a demographic connection with future school requirements.

Total population change depends on natural change and net migration. Natural change is births minus deaths. If births are fewer than deaths, natural change is negative. However, people entering the country can compensate for that loss. Positive net migration means more people enter than leave. If the number entering is approximately equal to the natural decrease, the total population can remain stable. Therefore, option A correctly explains the situation.

For example, if deaths exceed births by 10000 and net migration adds 10000 people, the total change is \(-10000+10000=0\). High out-migration would make the population fall further, and equal births and deaths contradict the condition. Increasing land area does not directly add people. Thus, positive net migration is the relevant factor.

Population changes through natural increase and migration. Natural increase is positive when births exceed deaths. Net migration is positive when in-migration exceeds out-migration. If both components are positive, both add people to the total population rather than cancelling one another.

In this situation, births contribute a gain after deaths are subtracted, and more people enter than leave through migration. Therefore the combined population change is positive, so total population will increase. Option A is correct. The amount of increase cannot be calculated without actual numbers, but its direction is clear. Options saying the population must decline, remain stable, or have a zero result contradict the two positive components.

Total population change has two relevant components here: natural change and net migration. Natural change is births minus deaths. Net migration is in-migration minus out-migration. If deaths exceed births, the first component is negative; if more people leave than enter, the second component is also negative. Both reduce the total population.

Because both effects act in the same direction, total population will decline, assuming the stated differences are genuine and no omitted component reverses them. Natural increase is not positive when deaths are higher than births. Therefore, option A is correct. The word “necessarily” makes the stability statement wrong because neither component is balanced.

Total population growth is the sum of natural increase and net migration. Natural increase measures the difference between births and deaths, while net migration measures arrivals minus departures. Therefore net migration rate equals total growth rate minus natural increase rate. Here it is \(1-1.4=-0.4\) percent. The negative sign means departures exceeded arrivals, so option A is correct.

Natural increase alone would have raised the population by 1.4 percent, but the actual total increase was only 1 percent. The difference of 0.4 percentage points must therefore come from net out-migration. A positive migration rate would have made total growth greater than 1.4 percent, not smaller. Thus the indication is approximately negative 0.4 percent.

Total population growth is composed of natural increase and net migration. Natural increase accounts for births minus deaths, while net migration accounts for the balance between arrivals and departures. Therefore, when total growth and natural increase are known, net migration is found by subtraction.

Net migration rate = total growth rate − natural increase rate = \(2.0\%-1.2\%=+0.8\%\). The positive sign means immigration exceeds emigration by that rate, adding to the natural increase. Hence option B is correct. A negative value would mean that outward migration reduced population growth, but the given total rate is higher than the natural rate, so the migration contribution must be positive.

Housing availability per person depends on both the number of people and the number of housing units. If population grows faster than the housing supply, the same homes must be shared by more people. This reduces the average housing space available to each person, even if the total number of homes has increased somewhat.

Therefore, option A is correct: housing availability per person can decline when housing construction grows more slowly than population. This situation may produce crowding and pressure on rents and services. If construction grew faster than population, availability per person would generally improve. Equal births and deaths would not by themselves create population growth, and rural residence does not answer the supply-demand comparison.

Per-capita food availability means the amount of food available, on average, for each person. It depends on the ratio of total agricultural production to total population. If production grows faster than population, the numerator of this ratio rises more quickly than the denominator, so food available per person can increase.

Thus option A is correct. For example, if population becomes 1.10 times its former size but food production becomes 1.20 times as large, the amount per person rises because production has grown relatively faster. This does not mean every person receives exactly the same amount, but it shows the possible overall effect. The other choices either reverse the relationship or make claims unsupported by the information.

A declining growth rate means that the population is increasing more slowly than before; it does not mean that the total population has already become small or started falling. A large population base can continue to add many people even at a lower percentage rate. In addition, rising consumption per person can increase demand for water, food, energy, land, and other resources.

Therefore option A is the best explanation: a large total population and higher per-capita consumption can still increase resource demand. The other choices use incorrect absolute claims. A lower growth rate does not always reduce resource use, population size remains relevant, and total population declines only when the growth rate becomes negative, not merely when it falls. Both population scale and consumption level must be considered.

Births and deaths show natural change, but they do not account for people moving across a country's borders. In-migration adds residents, while out-migration removes residents. Consequently, a country can have positive natural increase but little total growth if many people leave, or rapid total growth if many people enter. Migration can therefore change the actual population size independently of births and deaths.

Option A is correct. A complete population-change calculation combines natural increase with net migration: \(Total\ change = Births - Deaths + (Immigration - Emigration)\). The other choices are false because migration does not automatically eliminate births or deaths, and it does not change only land area. Its direct demographic effect is on the number and composition of residents.

Long-term population growth cannot be understood from one final number or one year's population alone. A useful analysis follows several years of births, deaths, migration, age structure, and growth rates. Together, these measures show whether change comes from natural increase, migration, or shifts in the age composition. Therefore option B is the complete and most useful combination.

A time series reveals direction, speed, and turning points. Birth and death data explain natural change, migration explains movement across boundaries, and age structure helps indicate future population potential. Land area may help calculate density, but it does not explain population growth by itself. A single total hides these processes, so options A, C, and D are insufficient.

Correct answer: C, 2.5 million people, or 25 lakh. Absolute increase is found by multiplying the initial population by the growth rate in decimal form. Convert 1.25 percent to 0.0125. Then calculate 200,000,000 × 0.0125 = 2,500,000. Therefore, the population increases by approximately 2.5 million in one year. A, 1 million, is too small and would correspond to only 0.5 percent of 200 million. B, 1.5 million, also uses an incorrect rate. D, 5 million, doubles the correct increase and would represent a 2.5 percent rate. The question asks for an absolute number of people, not merely the percentage. Memory cue: percentage increase becomes an absolute increase after multiplying by the original population.

Correct answer: B, positive 3 per thousand. Natural increase equals births minus deaths: 9 − 12 = −3 per thousand. This means the population would lose 3 people per thousand through natural change. Because total growth is zero, positive net migration must replace exactly those 3 people per thousand. The equation is total growth = natural increase + net migration, so 0 = −3 + net migration; therefore net migration = +3 per thousand. A is wrong because negative migration would add to the decline and make total growth −6 per thousand. C is wrong because 21 per thousand incorrectly adds the birth and death rates instead of finding their difference. D is wrong because zero migration would leave the natural decrease uncompensated. Memory cue: when natural change is −3 and total change must be 0, migration must be +3.