Population Growth

The correct answer is A. A large young population can sustain population growth as people reach reproductive ages. If many young adults migrate out, fewer potential parents remain in the country, so future births and the potential for continued growth may decrease. The effect is possible rather than certain because it also depends on the ages and number of those leaving and on other population factors.

Total population change combines natural change with net migration. A negative natural change means that births and deaths alone reduce the population. Positive net migration can offset that reduction. Adding the two signed quantities, rather than adding their absolute sizes, gives the net result.

Here, total change is \(-6000+6000=0\). The gain from net migration exactly balances the natural loss, so there is no net numerical change in the population. Therefore, option C is correct. This does not mean that no people moved or that the population’s composition stayed identical; it means only that the final total is unchanged.

A natural increase rate of 17 per thousand means that 17 people are added naturally for every 1,000 people in the population. Since the population is 30 million and migration is zero, there is no migration gain or loss to adjust the result. The rate should be converted by dividing by 1,000.

The calculation is \(30,000,000\times\frac{17}{1000}=510,000\). Thus the approximate natural increase in one year is 510,000 people, so option B is correct. With zero migration, this natural increase is also the total population increase for the year. Confusing 17 per thousand with 17% would produce a much larger and incorrect value.

A natural increase rate of -2.5 per thousand means that the population experiences a natural loss of 2.5 people for every 1,000 people during one year. The population is 60 million, or 60,000,000. Convert the rate to a fraction and multiply: \(60,000,000\times\frac{-2.5}{1000}=-150,000\). The negative sign represents a decline.

Therefore, the approximate natural change is a decrease of 150,000 people, so option B is correct. This calculation includes only births and deaths; migration is not included in natural change. A decrease of 100,000 or 250,000 results from using the wrong rate or base. The supplied explanation correctly interprets the negative value and reaches the correct option.

Natural growth and net migration are signed rates, so a negative value must be added algebraically rather than treated as a positive magnitude. The natural growth is -0.8%, showing a natural decrease. Net migration is +1.1%, showing an increase from people entering the country.

Adding them gives \(-0.8+1.1=+0.3\%\). Thus the total population still grows by 0.3%, making option C correct. Adding the absolute values to obtain 1.9% would be wrong because it ignores the negative sign of natural growth. Migration slightly exceeds the natural decline.

Total growth is the sum of natural increase and net migration: total growth = natural increase + net migration. Therefore, net migration can be found by subtracting natural increase from total growth. The signs are important because negative migration represents net out-migration.

Using the given rates, net migration = \(-0.6 - (+0.4) = -1.0\) percent. Thus, net migration is negative 1 percent, meaning more people leave the country than enter it by that amount. Option A is correct. The positive natural increase of 0.4 percent is more than offset by the negative migration balance.

Fertility decline affects school-age population with a delay. Children born before fertility began to fall do not disappear from the population when the birth rate changes. A large group born in earlier years continues to move through primary and secondary school ages, so schools may still have many students for several years.

This is called a population or age-structure effect: the size of earlier birth cohorts influences present enrolment. Only after the smaller cohorts born following the fertility decline reach school age will enrolment begin to fall substantially, assuming migration and schooling patterns do not offset the change. Thus option A is correct. Declining fertility does not immediately increase demand, and schools do not create population growth.

Population is divided into age cohorts, and each cohort becomes older over time. A country may have had many births in earlier years, creating a large group that is now reaching working age. At the same time, if recent births are fewer, the child population can decline. Thus the working-age group may continue increasing for some time even while the child group becomes smaller.

Therefore option A is the best explanation. This pattern is an example of population momentum caused by the age structure. Option B is wrong because working-age population is strongly connected with past births. Option C assumes all age groups change immediately in the same direction, which is not how cohorts work. Migration may also matter, so option D is too absolute. The supplied answer is correct.

A population can keep the same total size while its internal composition changes. Net migration is the number entering minus the number leaving, so equal numbers entering and leaving produce zero net migration. However, the ages and characteristics of those two groups still matter for the age structure.

Here, working-age people enter while elderly people leave. The total count can therefore remain stable, but the share of younger or working-age residents can rise and the share of elderly residents can fall. This makes the population structure younger, so option A is correct. A structural change does not require a change in total population, and natural increase is not guaranteed merely by this movement.

The Rule of 70 connects annual growth rate and doubling time through the approximate formula growth rate = 70 divided by doubling time. The doubling time is given as 50 years, so substitute 50 into the denominator. The rate obtained is expressed in percent per year, because the Rule of 70 uses percentage growth rates.

Growth rate ≈ 70 ÷ 50 = 1.4 percent per year. Therefore, option C is correct. This means that a population growing at roughly 1.4 percent annually would take about 50 years to double if the rate stayed constant. A rate of 1 percent would imply a doubling time near 70 years, while 2 percent would imply about 35 years. The rule is an estimate rather than an exact demographic calculation.

The Rule of 70 is a convenient way to estimate how long a population takes to double when its annual growth rate is approximately constant. The formula is doubling time approximately equal to 70 divided by the growth rate in percent. Since the rate is 0.8 percent, use 0.8 directly in the division rather than converting it to 0.008.

Doubling time ≈ 70 ÷ 0.8 = 87.5 years. Therefore, option C is correct. The long time is reasonable because 0.8 percent is a relatively slow annual increase. For comparison, a 1 percent rate would give about 70 years, so a rate below 1 percent should require more than 70 years. The estimate assumes the rate remains broadly unchanged and does not model yearly demographic fluctuations.

When growth occurs in successive years, the second percentage is applied to the population after the first year's growth. Therefore, the two rates should be combined using growth multipliers, not simply added. A 12% increase gives a multiplier of 1.12, and an 8% increase in the next year gives a multiplier of 1.08.

The combined multiplier is \(1.12\times1.08=1.2096\). This means the final population is 120.96% of the original, so the total increase is 20.96%. Therefore option B is correct. Adding 12% and 8% gives only 20% and ignores the extra 8% applied to the population already enlarged during the first year.

Successive percentage changes must be applied to the changing population, not both to the original number. Let the initial population be 100. A 15 percent increase changes it to 115. The later 10 percent decrease is calculated from 115, so it removes 11.5 and leaves 103.5.

The final value is 103.5 compared with the starting value of 100, which is a 3.5 percent increase. Equivalently, use \(1.15\times0.90=1.035\). Therefore, option A is correct. Simply subtracting 10 from 15 gives a 5 percent increase, but that is inaccurate because the second percentage uses a different base.

Ageing usually refers to a rising share of older people in the total population. Large-scale in-migration of young adults increases the working-age group and changes the age structure. For a period, older people then make up a smaller proportion of the total population, even though the absolute number of older residents need not fall.

Therefore, young adult migration may temporarily slow the pace at which the population appears to age, making option A correct. It cannot be said that ageing will end immediately or that the elderly population will automatically double. The exact long-term effect depends on migrants’ ages, future births, deaths and later migration.

Total population and the population of one age group do not always move in the same direction. A country’s total can rise because the numbers of children or elderly people increase, while the working-age group falls. Another possible reason is that many working-age adults migrate out of the country. Age groups are separate parts of the total population, so growth in one or more groups can offset a decline in another.

Therefore, option A is the most appropriate explanation. Option B is wrong because total growth does not require every age group to grow. Option C wrongly treats the working-age group as identical to the total, and option D is an extreme claim unsupported by the information. Population totals must be examined together with age structure and migration.

Child mortality is the number of children who die at an early age. When it falls, a larger share of children born survives. If the birth rate remains high, many births continue while fewer children are lost, so the natural increase can become larger at first. This describes an initial demographic effect, not an inevitable long-term outcome.

The question says that mortality falls sharply but births stay high for several years. More surviving children are therefore added to the population, which can accelerate population growth. Hence option A is correct. Growth does not immediately become negative, and births do not become zero. Later, social and economic changes may reduce fertility, but that later possibility does not change the initial result.

Age-group growth can differ from total population growth because people of different ages contribute differently to population change. A city may receive many migrants who are young adults, while the number of children changes only slightly. Such migrants increase the total population without immediately increasing the 0-to-14 age group by the same amount.

Here total population rises by 25 percent, but the child group rises by only 3 percent. This pattern is consistent with migration of people mainly in working or young-adult ages, perhaps toward jobs or education. A sharp rise in births would usually affect the child group more strongly. Therefore option A is the most plausible answer.

Gross migration counts all movement into and out of a region, while net migration is only the difference between arrivals and departures. Therefore, net migration near zero means the numbers may balance, but it does not mean that the same kinds of people moved. The characteristics of movers can still alter population composition.

For example, if many young skilled workers arrive while older or less-skilled people leave, total population may remain almost unchanged, but the shares of age groups, skills, and possibly sexes will change. Hence option A is correct. Zero net migration does not mean zero movement. Gross migration can have important demographic effects even when its numerical balance is nearly zero.

A simple one-year increase is found by applying the percentage rate directly to the starting population. Convert 0.625 percent into a decimal by dividing by 100, then multiply it by 160 million. This calculation assumes the stated rate applies for one year and does not involve compounding.

The increase is \(160000000\times\frac{0.625}{100}=1000000\). Thus approximately one million people, or 10 lakh people, are added in one year. Although 0.625 percent is less than one percent, it is applied to a very large population, so the numerical increase is substantial. Therefore, option C is correct.

Percentage decrease is calculated by comparing the amount lost with the original population. The population falls from 36 million to 34.92 million, so first find the absolute decrease: 36 − 34.92 = 1.08 million. This value must be divided by the original 36 million, not by the final population, before converting it to a percentage.

Percentage decrease = (1.08 ÷ 36) × 100 = 3 percent. In full numbers, the decrease is 1,080,000 and \(1,080,000 ÷ 36,000,000\) × 100 also equals 3 percent. Therefore, option B is correct. The number 1.08 million describes the amount lost, while 3 percent describes that loss relative to the starting population. The value 10.8 percent confuses the number 1.08 million with a percentage.

A falling birth rate, continued population growth, and a rising elderly share can occur together. Population totals do not respond instantly to a change in births. People already living in the country, demographic momentum, longer life expectancy, and possible positive migration may keep the total population increasing for some time.

At the same time, fewer births reduce the proportion of children. If people live longer, older age groups become a larger share of the population. Therefore slower growth and population ageing can happen together, so option A is correct. Option C is too immediate, while option B incorrectly assumes that a growing total must always have a young age structure.

A high birth rate adds people, but population growth depends on the balance between births and deaths rather than on births alone. Natural increase is calculated as births minus deaths. Therefore, a country with both high birth and high death rates may have a small natural increase, a large natural increase, or even a decline, depending on the difference between the two rates.

For example, 30 births and 28 deaths per thousand give natural increase of only 2 per thousand. Thus the high birth rate by itself does not show rapid growth. Option A is correct because it states that natural increase depends on the difference between births and deaths. The other choices either confuse mortality with migration or make claims that are not generally true.

Natural increase depends on the gap between the birth rate and the death rate. If the death rate falls rapidly while the birth rate remains high, many fewer people die but births continue at a relatively high level. The difference between births and deaths therefore becomes larger.

During this interval, natural increase accelerates and population grows more rapidly. This pattern is typical of an early stage of demographic transition, although the answer does not require naming that model. Therefore option A is correct. Population would not immediately decline, and growth would not be zero unless births and deaths were equal. Migration is not needed to produce this effect.

Zero population growth describes the final balance, not the size of births and deaths separately. A country can have many births and many deaths that nearly balance, or it can have very few births and very few deaths that also balance. These situations produce the same net growth but different demographic structures and population processes.

The high-birth, high-death country may have a younger population and a faster turnover of people. The low-birth, low-death country may have an older population and slower demographic change. Thus, equal zero growth does not make the countries identical. Their age structures, fertility, mortality, and population dynamics may differ, so option A is correct.

Migrants aged 18 to 30 are generally in the working-age or higher-education group. When many such people arrive, the city must quickly provide opportunities for employment or study, places to live, and ways to travel between homes, workplaces, and institutions. Rental housing is especially relevant because newer migrants may not own homes.

Therefore, option A is the most suitable answer: jobs, rental housing, and public transport. Elderly care and pensions mainly respond to an ageing population, not primarily to an influx of young adults. Agricultural land is not the immediate urban demand described. Other needs, such as schools and health services, may also rise later, but they are not the best choice among the listed options.