Age Structure

In-migration of young adults can quickly increase the working-age share because migrants are already near or within working age. This may reduce the dependency burden temporarily and support the labour force. However, migration does not permanently change the ageing process. Migrants grow older, and very low fertility continues to produce small younger cohorts among the resident population.

Therefore, the working-age advantage may be temporary because migrants will also age, making option B correct. Option A is too absolute: ageing cannot be assumed to disappear permanently. Option C does not follow from migration, and option D is wrong because sustained low fertility continues to affect the future age structure. The exact duration of the advantage depends on migrant numbers, ages, retention, fertility, and later migration patterns.

A total dependency ratio of 75 means that dependents equal 75 percent of the working-age population. The working-age share is approximately 57.1 percent. If the dependent share is \(D\), then \(\frac{D}{57.1}\times100=75\), so \(D=57.1\times0.75=42.825\) percent.

Rounded to one decimal place, this is about 42.8 percent, conventionally represented by the offered answer 42.9 percent. The population-balance check is also useful: \(57.1+42.9=100\) percent. Therefore, option B is the intended and mathematically matching choice. The value 75 is not the dependent share; it is the ratio relative to working-age people.

The total dependency ratio of 40 means that dependents equal 40 percent of the working-age population. The working-age share is about 71.4 percent. Let the dependent share be \(D\). Then \(\frac{D}{71.4}\times100=40\), so \(D=71.4\times0.40=28.56\) percent.

Rounded to one decimal place, the dependent share is 28.6 percent, making option B correct. The result is consistent with the population split because \(71.4+28.6=100\) percent. Option C, 40 percent, incorrectly copies the dependency ratio as though it were a share of the total population. The ratio and the population share use different denominators, which is why they are not numerically identical.

A population pyramid follows cohorts, meaning groups of people born around the same period. As time passes, a cohort becomes older and moves into the next age categories. The people who are currently 40 to 54 years old will be 15 years older after fifteen years.

Adding 15 years to both ends gives ages 55 to 69. Therefore, the present bulge in the 40–54 group will appear mainly in the 55–69 group later, apart from effects of mortality and migration. Option C is correct. The 40–54 group would describe the same people only if no time had passed, while the younger options move the cohort in the wrong direction.

The child dependency ratio places the child population in the numerator and the working-age population in the denominator. A ratio of 40 means that the child share is 40 per 100 units of working-age share. Let the working-age share be \(W\), and use the given child share of 24 percent.

The equation is \(\frac{24}{W}\times100=40\). Thus \(24\times100=40W\), giving \(W=2400/40=60\) percent. Therefore, option B is correct. Checking the result, \(\frac{24}{60}\times100=40\). Choosing 80 percent would give only \(\frac{24}{80}\times100=30\), so it cannot satisfy the stated dependency ratio.

Total dependency is the sum of child dependency and elderly dependency because both are measured against the same working-age base. First remove the child component from the total to find the elderly dependency. Then convert that ratio into the elderly share of the total population using the given working-age share.

Elderly dependency = \(60-20=40\). If the elderly share is \(E\), then \(\frac{E}{62.5}\times100=40\). Hence \(E=62.5\times0.40=25\) percent. Therefore, option C is correct. The remaining population check also works: child plus working-age plus elderly shares are not required to be recalculated, but the elderly value correctly produces a ratio of 40 against a 62.5 percent working-age base.

If dependents form 40 percent of the whole population, the working-age share is the remaining part: \(100-40=60\) percent. The stated dependency ratio provides a direct check. Dividing the dependent share by the working-age share gives \(\frac{40}{60}\times100=66.666\ldots\), which rounds to about 66.7.

Therefore, the working-age share is 60 percent, and option C is correct. The value 66.7 is the dependency ratio, not the working-age percentage, so option D confuses a ratio with a population share. This question also illustrates why the two measures should be kept separate: a share describes part of the total population, while a dependency ratio compares dependents specifically with working-age people.

Population ageing and total population growth describe different things. Ageing means that older people make up a larger proportion of the population, often because fertility has fallen and people live longer. Total population growth, however, depends on the balance between births and deaths and also on migration.

These processes can occur at the same time. A country may have a rising share of older people while births still exceed deaths, or while immigration adds more people. Thus, an ageing population does not necessarily mean that the total population is shrinking. Option B is correct. The other choices wrongly treat ageing and population growth as mutually exclusive or unrelated.

A large working-age cohort is a demographic wave. When it reaches older ages, the country should expect greater demand for pensions, health services, and possibly long-term care. At the same time, many members of that cohort may retire or leave employment, so the economy may need replacement workers, productivity improvements, or carefully planned migration and training.

For these reasons, planning for pensions, elderly health, and labour-force replacement should begin in advance, making option B correct. Primary-school expansion and child vaccination are valuable policies, but they do not directly prepare the country for the near-term ageing of this large cohort. Expanding farmland also does not address retirement income, medical needs, or the likely reduction in available workers. Advance planning allows financing and services to adjust gradually.

The total dependency ratio combines child dependency and elderly dependency, both usually measured relative to the working-age population. If the child population falls, child dependency will generally place less pressure on workers. If the total ratio still does not fall, another part of the ratio must be increasing or offsetting that decline.

The most likely explanation is rising elderly dependency. More older people can increase the elderly component enough to cancel the reduction in child dependency, leaving total dependency unchanged. Option A expresses this offsetting effect. Rapid growth of the working-age population would normally reduce dependency if the dependent groups did not rise, and the other choices do not explain the unchanged total.

Dependency ratios are relative measures. Child dependency compares children with the working-age population, while elderly dependency compares older people with the working-age population. If the number of children stays stable but the working-age population grows, the same number of children is spread over a larger denominator, so child dependency may fall.

For elderly dependency, both the elderly population and the working-age population are increasing. Its direction depends on which group grows faster in relative terms. If elderly people grow faster, elderly dependency rises; if the working-age group grows faster, it may fall. Therefore, option A is the only careful conclusion. The other options make absolute claims that the given information cannot support.

The total dependency ratio can improve even while pension pressure becomes stronger, because the two types of dependency may move in opposite directions. A large fall in child dependency can reduce the combined ratio, while a smaller rise in elderly dependency can still increase the number of pension beneficiaries and the financial burden on pension systems.

In the stated case, child dependency falls rapidly and elderly dependency rises slowly. The fall is larger than the rise, so total dependency declines overall. However, the growing elderly component creates greater pension needs. Therefore, option A is possible and best explains both observations. A falling elderly population would not explain rising pension pressure, and the other options are inconsistent.

The shape of a population pyramid gives clues about the size of different age groups. A broad middle means that many people are currently in the working-age range. A broad upper section means that the older population is also substantial. In contrast, a very narrow base means that relatively few children are being born and that younger future cohorts will be small.

Thus, the pyramid indicates a large present working-age group and a considerable elderly group, while the narrow base points to low recent fertility and smaller future youth cohorts. Option A combines all three observations. The pyramid does not show an extremely youthful population or very high fertility; those conditions would normally produce a broad base.

Expert analysis of age structure needs both a picture of the present and evidence about change over time. Age shares show the current distribution, while dependency ratios indicate the relative burden on working-age people. Cohort progression helps trace how groups will move through the age structure. Labour-force participation shows whether working-age people are actually economically active, and migration can alter the size and age of groups.

Service demand connects these demographic facts to planning for schools, health care, pensions, housing, and care. Therefore, the complete combination is age shares, dependency ratios, cohort progression, labour participation, migration, and service demand, which is option C. A pyramid alone is descriptive, and birth and death rates alone do not show the full current structure or its economic consequences. Child and elderly percentages are useful but insufficient for expert analysis.

Persistently low birth rates make each new child cohort smaller than earlier cohorts. At the same time, very low mortality means that more people survive to old age and live longer. Over several decades, the smaller number of children reduces the young share, while improved survival increases the number and proportion of older people. The country may still have a substantial working-age population for some time, but its age structure gradually shifts toward older ages.

Choice B is therefore the best answer. Choice A would be more likely with high fertility and large child cohorts, not with persistently low fertility. Choice C is unrealistic because age groups do not automatically become equal. Choice D is an extreme and immediate claim; the working-age group does not disappear, although its relative share may later decline as cohorts age. The result is population ageing, not instant structural change.

The total dependency ratio is the combined burden of young dependants and old-age dependants compared with the working-age population. In a simplified expression, total dependency equals youth dependency plus old-age dependency. Therefore, if the total ratio falls while old-age dependency rises, the youth component must be falling by a larger amount than the rise in the old-age component.

Option A is the only logical interpretation. This pattern can occur when fertility declines and the share of children becomes smaller, even while people live longer and the elderly share increases. B would tend to raise, not lower, the total ratio. C is impossible as a description of a society with measured dependency, and D cannot be true because old-age dependency is one part of the total and cannot exceed it.

The proportion of elderly people indicates the age structure, but it does not by itself determine total health expenditure. Medical spending among older people depends greatly on their health condition, disability, disease burden, access to care, prices, and the organisation of the health system. A country may have 18% elderly people while many of them remain healthy and independent for a long period. In that situation, their average need for expensive treatment may be lower than expected.

High healthy life expectancy is therefore the best explanation among the choices. It means people live many years in relatively good health, delaying or reducing intensive medical care. The statement that elderly people never use health services is an unreasonable absolute claim, and age structure does affect health demand. The elderly population cannot be zero when it forms 18% of the total. Hence option A is correct.

The dependency ratio compares dependent-age people with the working-age population. Here, children aged 0–14 and older people aged 65 and above are counted as dependents. Their total is 24 million + 8 million = 32 million. The working-age group, aged 15–64, contains 56 million people.

The total dependency ratio is calculated as \(\frac{32}{56}\times100\). Since \(32\div56\) is about 0.5714, the result is about 57.1 dependents per 100 working-age people, or approximately 57. It is not 43, because that would omit or mishandle one dependent group. Therefore option B is correct.

A decline in fertility affects the number of babies being born now, but it does not immediately remove children who were born in earlier years. Population has age structure, so different birth cohorts move through school ages at different times. If a relatively large cohort was born before fertility declined, many of those children may still be entering or attending school. Their presence can keep total enrolment rising for several years, even while the proportion of children in the whole population begins to fall.

Option A correctly explains this time lag between lower births and school demand. Option B is the opposite of the demographic effect. Option C ignores the direct connection between the size of school-age cohorts and enrolment. Option D is implausible and unsupported, since elderly people do not replace children in ordinary school-age enrolment. Thus, A is the most appropriate explanation.

The old-age dependency ratio compares the elderly population with the working-age population, not directly with the total population. If the working-age share is 64 percent and the ratio is 25, then elderly people equal 25 percent of the working-age share. Let E represent the elderly percentage of the total population. The relationship is \(E/64\times100=25\), so \(E=64\times25/100=16\) percent.

Therefore option B is correct. A value of 25 percent would be the dependency ratio itself, not the elderly share of the whole population. The calculation assumes that the stated ratio uses the usual definition of elderly population divided by working-age population, multiplied by 100. Under that standard definition, the answer is 16 percent.

A growing elderly population can increase the potential need for pensions, but the amount paid from the government budget depends on how the pension system is designed. If public pensions cover only some older people, or if employer-based and private pensions provide much of the income, government expenditure may rise more slowly than the elderly population. Eligibility rules and benefit levels can also affect the pattern.

Therefore option A is a possible institutional explanation. Older people do have a relevant connection with pensions, and they do not return to working age. Government spending does not always fall when the elderly share rises; it depends on coverage, financing and policy. The answer appropriately identifies limited public coverage or a larger private role without claiming that ageing has no fiscal effect.

The three broad age groups together make 100 percent of the population. Initially, the working-age share is \(100-40-8=52\) percent. After the change, it is \(100-25-15=60\) percent. The difference is \(60-52=8\) percentage points. The fall in the child share is 15 points, while the rise in the elderly share is 7 points, so the remaining working-age share rises by a net 8 points.

Option B is correct. The answer is an increase of 8 percentage points, not 8 percent relative growth. Option A does not account correctly for both changed groups, and option C mistakes the child-share decrease for the working-age change. Option D reverses the direction. This calculation assumes the stated child and elderly shares cover the non-working-age groups and that all age shares total 100 percent.

A large young population creates potential, not an automatic demographic dividend. Female education and health influence labour-force participation, fertility decisions, child nutrition, skills and the productivity of the next generation. If these conditions remain weak, many people may enter working age without adequate health, education or employment opportunities, so human capital and economic capacity remain limited. Option D is wrong because population size alone cannot guarantee development; institutions, skills and inclusion are also essential.

The three age groups together make 100 percent of the population. The child share is therefore \(100 - 22 - 58 = 20\) percent. Children and elderly people are dependents in this simplified calculation, so the total dependent share is \(20 + 22 = 42\) percent. The dependency ratio compares dependents with the working-age population, not with the whole population: \(42 \div 58 \times 100 \approx 72.4\). It is therefore about 72.

Option A is correct. The value 42 is the dependent share, not the dependency ratio, so option B confuses two related measures. Option C uses the wrong child share, and option D simply repeats the given age shares. The calculation assumes the listed groups cover the whole population and uses the usual ratio of dependents to working-age people.

A single unusually large age group does not prove one specific historical event. It might represent a genuinely large birth cohort, age-selective migration, inaccurate counting, or age heaping, in which people report a convenient rounded age. Because the neighbouring age groups are normal, the evidence is especially limited: the pattern needs comparison with earlier censuses, birth records, migration data, and data-quality checks before a cause can be assigned.

Option A is correct because it keeps both a real cohort effect and reporting error open. B and C are too certain; a baby boom or war effect would require supporting historical evidence. D is false because age pyramids can contain irregularities. The cautious interpretation is not indecision without reason; it is proper demographic analysis when one isolated bulge has several plausible explanations.