Population Growth

Total population change has two main components: natural increase and net migration. Natural increase equals births minus deaths. Net migration equals in-migration minus out-migration. If births exceed deaths, natural increase is positive, but the total population can still remain stable when people leaving the district approximately equal that natural increase.

Therefore, option A explains the situation. For example, if natural increase adds 1,000 people and net out-migration removes about 1,000, the total change is close to zero. High in-migration would normally raise the population, not keep it stable. Zero deaths is unnecessary, and an expanding land area does not determine population change directly.

The Rule of 70 is a quick way to estimate how many years a population takes to double when its annual growth rate is fairly stable. The approximate formula is doubling time \(=70\div\) annual growth rate in percent. It is an estimate, not an exact prediction.

With a growth rate of 2 percent, the calculation is \(70\div2=35\) years. Thus option A is correct. The rule does not require multiplying the rate by 70, subtracting it from population, or adding birth and death rates. Its usefulness depends on treating the rate as approximately constant during the period considered.

The Rule of 70 is a quick method for estimating how long a quantity will take to double when it grows at a steady annual percentage rate. The estimated doubling time is calculated by dividing 70 by the annual growth rate expressed as a number, not as a decimal. It is an approximation, so the actual time may differ slightly under changing conditions.

For a growth rate of 1 percent per year, apply \(\text{doubling time}=70\div1=70\) years. Therefore option C is correct. A rate of 2 percent would give about 35 years, which explains why option A is not suitable here. The estimate assumes continued growth at approximately the same rate and does not account for sudden changes in fertility, mortality, or migration.

Doubling time is the time required for a population to become twice its present size. When other conditions are similar, a higher growth rate reaches doubling sooner. The relationship is inverse: as the annual growth rate increases, the number of years needed for doubling decreases.

The Rule of 70 gives an approximate doubling time by dividing 70 by the percentage growth rate. At 1 percent, the time is about \(70\div1=70\) years. At 2 percent, it is about \(70\div2=35\) years. Thus, the country growing at 2 percent doubles sooner. Option D is correct. The starting population does not change this comparison when the rates are compared under similar conditions.

Answer: B, doubling time becomes very long. For a positive growth rate, doubling time is inversely related to the rate: when growth becomes smaller, the population takes longer to double. As the rate approaches zero from above, the required time becomes extremely long. A states the opposite relationship. C is unjustified because doubling time depends on the actual growth rate; 35 years is not universal. D also reverses the relationship. If the rate becomes exactly zero and remains zero, doubling would not occur through growth. Memory cue: slower growth means a longer wait to double.

Per-capita availability means the amount of a resource available for each person. It is found by dividing the total resource supply by the population. If the total supply remains fixed while the number of people increases, the denominator becomes larger, so the amount assigned to each person becomes smaller.

For example, suppose a fixed water supply is shared by 100 people and then by 200 people. Unless the supply increases, each person receives a smaller share in the second situation. This does not mean that resources vanish or that land area grows automatically. Therefore option A is correct: the same resources must be divided among more people. The concept concerns the share per person, not the total quantity available in the whole region.

Hospital capacity includes beds, doctors, nurses, equipment, and other facilities. If the city’s population rises by 10 percent while these resources remain unchanged, the same health system must serve more people. On average, available capacity per person falls. This may produce longer waiting times, crowded hospitals, heavier workloads, and more pressure on appointments and emergency services. The exact effect depends on health needs and service organisation, but pressure is the likely direction.

Option B is correct because it expresses this increased burden per person. Capacity does not automatically increase, so A is the opposite of what the conditions suggest. Hospitals do not become unnecessary, making C false. D is also incorrect because population size directly affects demand for health services. The question asks for the most likely result, not a guaranteed identical outcome in every hospital. The supplied answer and explanation are consistent.

When migration is the main driver of a city's population growth, the city must receive more people than it loses. In demographic terms, this means net migration is positive: arrivals exceed departures by a substantial amount. Births and deaths can still affect the total population, but they are not the main explanation in the situation described. The city may attract migrants because of jobs, education, services, safety, or other opportunities.

Therefore, option A is correct. Equal births and deaths would make natural increase zero, but they do not describe migration-led growth. A city can gain population without expanding its legal land area, so option C is too absolute. Migration also does not make the death rate zero. The word “mainly” allows other factors to contribute, but it requires arrivals to exceed departures if migration is producing growth.

Population change has two broad parts: natural increase and net migration. Natural increase is births minus deaths. Net migration is in-migration minus out-migration. Total change therefore equals natural increase plus net migration. A high birth rate may create a positive natural increase, but large out-migration subtracts people from the total.

If many working-age adults leave, the region’s actual population growth can be smaller than its natural increase. If migration losses are sufficiently large, total population could even remain unchanged or decline. Therefore, option A is correct. Out-migration does not increase population, and it does not make natural increase automatically zero.

Percentage growth must be calculated relative to each country's initial population. The first country rises from 50 million to 55 million, an increase of 5 million. Its percentage growth is \\(\\frac{5}{50}\\times100=10\\%\\). The second rises from 500 million to 520 million, an increase of 20 million, but its percentage growth is \\(\\frac{20}{500}\\times100=4\\%\\).

Therefore, option A is correct: the first country has the higher percentage growth. The second country has the larger absolute increase, but absolute increase and percentage growth are not the same measure. The larger initial population makes the second country's 20 million increase a smaller fraction of its starting population. The figures are already expressed in consistent units.

A total increase of 25 percent means the final population is the original population plus 25 percent of it. In symbols, if the initial population is P, the final population is \(P+0.25P=1.25P\), which is 125 percent of the initial value. This conclusion follows directly from the meaning of cumulative percentage increase.

Therefore, option B is definitely correct. The information does not tell us that growth was exactly 2.5 percent every year; annual rates could vary, and compounding would also matter. It also does not identify the separate contributions of births, deaths, or migration. Thus options A, C, and D make claims that cannot be established from the stated total increase.

Net migration is the difference between in-migration and out-migration. It does not measure the total number of people who move. Consequently, large movements in both directions can cancel each other when the numbers entering and leaving are equal. A zero net value therefore does not necessarily mean that there was no movement.

For example, if 100,000 people enter and 100,000 people leave, net migration is \(100000-100000=0\), but 200,000 movements have occurred in total. Thus, the correct condition is that in-migration and out-migration are both large and equal. Option A is correct. “Nobody moves” is another situation producing zero net migration, but it does not describe very large movement.

Total population change includes both natural increase and migration. Natural increase is births minus deaths: \(1500-1000=500\). Net out-migration of 600 means 600 more people leave than enter, so migration contributes \(-600\) to the population change. Combining the two components gives \(500-600=-100\).

The negative sign means the population decreases rather than increases. Therefore, the total population change is a decrease of 100, so option A is correct. A decrease of 1100 would incorrectly add the deaths and the out-migrants without accounting for births. A natural increase of 500 ignores migration, while an increase of 100 reverses the effect of net out-migration. The supplied calculation is accurate.

Answer: B, an increase of 300. First calculate natural change: births − deaths = 900 − 1100 = −200, meaning a natural decrease of 200. Then add net in-migration: −200 + 500 = +300. Therefore, the population increases by 300 overall. A considers births and deaths but ignores migration. C counts only migrants and ignores the natural decrease. D incorrectly adds births, deaths and migrants, even though deaths reduce population. The key sequence is: natural change = births − deaths; total change = natural change + net migration.

Natural increase depends on the difference between births and deaths. If the death rate falls rapidly while the birth rate remains high, many births continue but fewer deaths occur. The gap between births and deaths therefore becomes wider, causing the population to grow more quickly at first. This is a common early pattern in demographic transition when improvements in sanitation, nutrition, or health reduce deaths before families substantially reduce births.

Option A is correct because it describes acceleration of natural increase. Immediate population decline would require deaths to exceed births, while zero growth would require them to be equal. The end of migration does not follow from the information, since migration is a separate component of population change. The question asks for the initial response, so later effects such as falling birth rates or changing age structure should not replace the direct result of fewer deaths and continued high births.

Natural increase is the difference between the birth rate and the death rate, without counting migration. If the birth rate later falls while the death rate does not rise correspondingly, the gap between births and deaths becomes smaller. The number added naturally to the population each year therefore decreases, so the pace of natural increase generally slows. Total population may still continue to grow for some time, but it grows more slowly rather than necessarily falling immediately.

Option B is correct. Option A is opposite to the expected effect of a declining birth rate. Option C is wrong because natural increase directly depends on the difference between births and deaths. Option D is unsupported: a fall in birth rate does not automatically cause death rate to rise. The word “generally” is important because the exact outcome depends on the levels and timing of both rates.

A growth rate of 1.25 percent means that 1.25 out of every 100 people is added in one year, assuming a simple one-year calculation. The population is 80 million, so we multiply it by 1.25 percent. The resulting increase is 1 million people, which is 10 lakh. Hence, choice C is correct.

Convert the percentage to a fraction: \(1.25\%=\frac{1.25}{100}=0.0125\). Then calculate \(80000000\times0.0125=1000000\). Since 1 million equals 10 lakh, the answer is 10 lakh or 1 million. Choice B, 0.8 million, would correspond to a rate of 1 percent, while choice D uses the percentage number without applying it correctly.

Answer: B, 19 million, which is 1.9 crore. First calculate the amount of the decline: 5% of 20 million = 20 × 0.05 = 1 million. Since the population declines, subtract this amount from the original population: 20 million − 1 million = 19 million. Equivalently, the remaining population is 95% of the original: 20 × 0.95 = 19 million. Option A subtracts 2 million, which would represent a 10% decline. Option C adds 1 million, so it represents a 5% increase rather than a decrease. Option D adds 5 million and does not apply the percentage correctly. Memory cue: after a decline, multiply by 1 minus the decline rate, not by the decline rate itself.

Total population tells us how many people live in a region, but it does not show their ages. School demand depends especially on the number and proportion of children who are likely to need primary or secondary education. Two regions may each have one million residents, yet the one with more children will need more classrooms, teachers, buildings, and educational resources.

Therefore, option A is correct. Land area does not determine school demand by itself, so B is insufficient. Adults and elderly people do not attend school in the same numbers as school-age children, making C false. Migration can have a particular age profile, so it can alter the child population and future demand; this makes D false as well.

A rapidly growing working-age population can provide a demographic opportunity because more people may produce goods, offer services, earn incomes, save, and support economic development. However, numbers alone do not guarantee this benefit. People need good education, useful skills, healthcare, and enough suitable jobs. Without these conditions, the same population may face unemployment, low productivity, or pressure on public services.

Therefore, option A is correct. When education, skills, health, and employment opportunities are adequate, the working-age group can contribute strongly to production and income. The other choices remove or weaken the conditions needed for this benefit. Closing industries, stopping job creation, or weakening health and education would turn potential opportunity into an economic challenge.

A positive growth rate means that the population is still increasing, because additions remain greater than losses overall. If the positive rate continuously declines, the population is increasing more slowly each period. If this pattern continues, the rate may approach zero, leading toward population stability rather than rapid expansion.

Therefore, option A is the most reasonable long-term direction. A declining positive rate does not mean that the population immediately doubles; doubling depends on the size and duration of growth. It also does not automatically become high again, and population growth has no necessary connection with the physical land area shrinking. The statement describes a likely demographic trend, not an absolute guarantee about every future year.

A percentage growth rate describes relative change, not the actual number of people added. The numerical increase depends on the initial population, called the population base. The calculation is \(\text{increase}=\text{base population}\times\text{growth rate}\). Thus the same rate can produce very different absolute increases in regions of different sizes.

For example, 1 percent of 100,000 is 1,000, whereas 1 percent of 10,000,000 is 100,000. Both regions have the same percentage rate, but the second adds far more people. Therefore, option A is correct. Percentage growth is still useful for comparing relative change, but it should be read together with the base population when planning housing, schools, jobs, health care, and other services. Land area alone does not tell us the number added.

Migration is often selective by age because young adults are generally more mobile when searching for employment, education, or better opportunities. If many young workers enter a city, the number and proportion of people in the working-age group may rise. This can also affect demand for housing, transport, and services, although the exact outcome depends on the migrants' ages and the existing population.

Option A is correct because it gives the most likely effect of young-worker in-migration. Option B is too certain and points to an opposite age group. Option C is unrealistic because migration does not make all age groups equal, while option D ignores the direct demographic effect of adding people with particular ages. The question asks what is likely, so “may increase” is appropriately cautious.

Per-capita agricultural land means the amount of agricultural land available for each person. It is found by dividing total agricultural land by total population. If the land area stays constant while the population rises, the denominator of this ratio becomes larger, so the amount available to each person must fall.

For example, if a fixed area is shared by 100 people and later by 200 people, each person receives only half as much land, assuming equal sharing. Therefore, option A is correct: the same agricultural land is being shared among more people. The other options contradict the stated condition or confuse total land with land per person. The conclusion is about the average available amount, not necessarily equal individual ownership.

Population growth is not explained by one number alone. Births add people and deaths remove people, together producing natural increase or decrease. Migration can change the population of a particular country or region even when natural change is small. The growth rate shows how quickly the total is changing, while age structure indicates future potential for births, workforce size, and dependency. Considering these factors together gives a fuller and more reliable analysis.

Option C is correct because it combines demographic processes, the rate of change, and the population’s composition. Looking only at births ignores deaths and migration; looking only at deaths has the same problem. Total population size describes the present scale but not why it is changing or what may happen next. A complete analysis should also interpret the factors in context, such as policy, health, fertility, employment, and movement across borders.