Age Structure

The old-age dependency ratio compares the population aged 65 and above with the working-age population aged 15–64. It is calculated as \(\frac{\text{older population}}{\text{working-age population}}\times100\). Here, the relevant figures are 20 percent and 62 percent; the 0–14 group is not used in this particular ratio.

The calculation is \(\frac{20}{62}\times100\approx32.26\), which rounds to about 32 older people per 100 working-age people. Therefore, option B is correct. The value is not 20 because the numerator must be compared with the working-age group, and it is not 38 or 44 because those do not result from the stated ratio.

An age pyramid shows how many people belong to each age group. A very narrow base means that recent births are relatively few, so fertility is low. A wide 35–54 group shows that a large generation has reached middle age. A relatively large group above 70 indicates that many people survive to older ages, usually reflecting longer life expectancy and advanced ageing. Together, these features describe a mature or ageing population rather than a rapidly growing youthful one.

Choice B is correct because it combines all three observations: low fertility, a large middle-aged cohort and substantial elderly population. A high-fertility population would normally have a broad base. A pre-industrial population generally would not show this large older-age share. Temporary migration might distort some age groups, but the stated shape alone most strongly indicates a broad demographic ageing condition, not only a temporary movement pattern.

The total dependency ratio is obtained by adding the youth dependency ratio and the old-age dependency ratio. Initially, it is \(50+12=62\). After the changes, it becomes \(28+24=52\). The difference is \(52-62=-10\), so the total ratio falls by 10 points. The increase in old-age dependency is 12 points, but the fall in youth dependency is larger at 22 points, producing a net decrease of 10.

Option B is correct. Option A would consider only the rise in old-age dependency and ignore the larger decline among youth. Option C uses the youth change alone, while D wrongly assumes the two changes cancel. The calculation concerns percentage points of the ratio, not a 10 percent relative decrease. Therefore total dependency decreases from 62 to 52.

A percentage is a share of the total population. Here the total population stays constant, so an increase in the elderly share from 12 percent to 19 percent means that more actual people are in the 65-and-above group. For example, if the total were 1,000,000, the elderly population would rise from 120,000 to 190,000. The exact total is not needed; because it is fixed and positive, the larger share necessarily represents a larger absolute number.

Option A is therefore definitely correct. The information does not prove that birth rate doubled, that the working-age population increased, or that children disappeared. In fact, other age groups may have declined or changed in different ways. The certain conclusion concerns only the elderly group: its numerical size increased when its percentage share rose while the total remained unchanged.

The governing concept is the effect of age-selective migration on population composition. Young working-age immigrants directly enlarge the working-age group and improve its balance relative to the elderly population. Consequently, the pace of population ageing may slow temporarily, even though low fertility continues. Option C is incorrect because immigration does not necessarily reduce the absolute number of elderly people; it mainly changes the relative shares of age groups. Migration can delay ageing pressures, but it cannot automatically remove long-term effects of sustained low fertility.

A demographic dividend is not automatic merely because the working-age share increases. One possible pathway is that more working-age people earn income, save part of it, and make those savings available for investment and capital formation. Investment can support productivity, employment, and economic growth when institutions and opportunities are suitable.

If the household savings rate falls, this savings-to-investment pathway becomes weaker. The country may still gain through employment or productivity, but the capital formation channel is reduced. The other choices do not describe the mechanism in the scenario: birth-rate measurement, geographic density, and elderly health are separate matters. Therefore option A is correct.

Population ageing means that the proportion of older people is rising, which can increase spending on pensions, health care, and support. However, chronological age alone does not show how many people need intensive help. Healthy life expectancy measures how many years people can expect to live in relatively good health. If it rises rapidly, many older adults may remain active, independent, and able to work or participate in family and community life for longer.

Therefore, option A is the possible outcome. The economic burden may still increase, but it can be lower than expected because dependency is not identical to being old. Option B wrongly treats every older person as immediately dependent. Option C is too extreme because health services remain necessary, and option D incorrectly dismisses the importance of age structure.

The dependency ratio compares the population usually considered dependent with the working-age population. Here the dependent groups are children aged 0–14 and older people aged 65 and above. The working-age group is aged 15–64. The formula is \(\text{dependency ratio}=\frac{0\text{–}14+65+}{15\text{–}64}\times100\). It indicates the number of dependents per 100 working-age people.

The dependent share is \(36+10=46\) percent, and the working-age share is 54 percent. Therefore, \(\frac{46}{54}\times100\approx85.2\), or about 85. Hence option C is correct. It is not 46, because 46 is only the dependent percentage, not the ratio relative to working-age people. The given age shares correctly add to 100 percent.

An age-group percentage is calculated as the number in that group divided by total population. Let the elderly share be a fixed positive fraction, represented by \(E/T\). If the elderly number rises by 25 percent, the new number is \(1.25E\). For the fraction \(E/T\) to remain unchanged, the total must also become \(1.25T\), or rise by 25 percent.

Therefore, under the stated conditions, total population also increased by about 25 percent; in fact, with an exactly constant share, the increase is exactly 25 percent. The other choices contradict this relationship or add information not given. Hence option A is the logical conclusion.

The base of an age pyramid represents recent births and younger children. A narrow base therefore suggests that current fertility or recent births are relatively low. A wide 20–29 age group, however, represents a large cohort that was born earlier, or it may result from many young adults moving into the country.

These two features can occur together: current births may have declined while a previously large generation has reached young adulthood, or migration may have enlarged that age group. Extremely high current birth rates would normally widen the base, not narrow it. The statements about no elderly people or all children being 20–29 are plainly inconsistent. Thus A is correct.

Total births depend on two linked factors: the number of women in reproductive ages and the average number of children each woman has. A country may have more women in those ages because of an earlier large birth cohort, yet still record fewer births if fertility per woman falls sufficiently. This can happen when marriage or childbearing is delayed, family size preferences change, or education and access to contraception improve. Therefore the number of potential mothers alone does not determine total births.

Choice A is correct because it explains how births can decline despite growth in the reproductive-age population. The birth rate does not have to be increasing; it may be falling. Age structure does affect births, so choice C is false. Women of reproductive age can have children, but the question concerns the average number, not biological inability. The conclusion is appropriately cautious because the exact fertility change is not provided.

The old-age dependency ratio compares the elderly population with the working-age population. It is calculated as elderly population divided by working-age population, multiplied by 100. Here the elderly group is 15 percent of the total population, and the ratio is 30.

Let the working-age share be W percent. Then \(15/W\times100=30\). Dividing by 100 gives \(15/W=0.30\), so \(W=15/0.30=50\) percent. The remaining population consists of other age groups, such as children, but that does not alter the calculation. Therefore option B, 50 percent, is correct. The ratio is not calculated by simply subtracting 30 from 15, because it is a relative measure with the working-age group as its denominator.

Population ageing can increase the need for care, but the amount of pressure on formal services depends partly on household organisation. In a multigenerational household, adult children or other relatives may help with daily tasks, supervision, transport and emotional support. This informal care can meet some needs and partly reduce the demand placed on hospitals, residential facilities or paid caregivers.

Option A is the most accurate because it says “some” care and “partly” reduces pressure. Family support does not remove the need for government health and social services, and it does not make the old-age dependency ratio zero. Nor does it ensure that every older person becomes financially independent. The effect is possible and conditional, not universal or complete.

A triangular age pyramid usually has a very broad base, showing a large share of children and relatively high fertility. It narrows quickly toward older ages when survival and life expectancy are lower. A more rectangular shape means that age groups are more evenly represented: the base is less wide and more people survive into middle and older ages. Over twenty years, this pattern is most commonly associated with falling fertility and falling mortality, producing greater balance across age groups.

Option A is correct because it explains both the narrower base and the wider survival pattern. Option B would tend to make the base broader, not rectangular. Option C would make the population structure less healthy and more sharply declining at older ages. Option D alone cannot normally explain a broad, sustained change across the whole age pyramid. The shape reflects demographic transition rather than only one migration event.

An old-age dependency ratio of 40 means that the elderly population equals 40 people for every 100 people of working age. The formula is \(\text{ratio}=\frac{\text{elderly population}}{\text{working-age population}}\times100\). Rearranging it gives elderly population equal to \(\frac{40}{100}\) of the working-age population.

The working-age population is 40 million, so the elderly population is \(0.40\times40=16\) million. Sixteen million is 1.6 crore, because one crore equals ten million. Therefore, option B is correct. The ratio is not 40 percent of the total population; it is 40 percent of the working-age population, which is why the denominator must be used carefully.

A very large working-age group can provide a temporary demographic dividend, but it is not permanent. If fertility remains very low, each new generation contains fewer children and therefore fewer people who will later enter the labour force. As the current large cohort grows older, the number of older dependants rises while replacement workers become fewer.

Option A states both parts of the long-term risk: a shortage of new working-age entrants and faster growth in old-age dependency. The child share will not necessarily keep rising, and elderly people will not fall to zero. The working-age share can decline after the present advantage passes. Migration, productivity and later changes in fertility may modify the outcome, but they do not remove the demographic logic.

The child and elderly groups together make up \(23\%+17\%=40\%\) of the total population. The remaining share is the working-age population: \(100\%-40\%=60\%\). Since the total population is 100 million, the working-age population is \(0.60\times100=60\) million.

Therefore, option B, 60 million or 6 crore, is correct. The options use both million and crore notation: 60 million equals 6 crore because 1 crore equals 10 million. The calculation asks for an absolute number, so giving only 60 percent would be incomplete. The result assumes the three age groups together cover the whole population without overlap.

Population ageing can reduce the proportion of people in working ages, which may place pressure on the number of workers supporting dependants. However, per-worker output does not remain fixed. Better technology, education, skills, machinery, infrastructure, management, and capital can allow each worker to produce much more. If productivity rises rapidly enough to offset the effect of a larger elderly share, total income can grow faster than population and per capita income can increase.

Option A is correct because it says income may still rise, not that it must rise in every ageing country. Option B is clearly unsupported: ageing cannot make per capita income automatically zero. Option C is wrong because ageing and productivity can interact, even though productivity depends on more than age structure. Option D reverses the relationship; higher productivity does not make an older population young.

Total dependency compares the dependent population with the working-age population. The dependent group commonly includes children and older people, so a simple measure is \(\text{total dependency} = \frac{\text{children + elderly}}{\text{working-age population}} \times 100\). If the working-age share stays nearly constant, a fall in child share may be offset by a rise in elderly share.

Therefore option A is the best conclusion: total dependency may remain roughly stable while its composition changes from more youth dependency to more old-age dependency. It is not certain to become zero, and both child and elderly dependency do not have to rise together. The age structure is clearly changing, so option D is also incorrect.

Age structure is a moving picture, not merely a set of present percentages. People belonging to one cohort gradually enter older age groups. Children today may later require secondary education, jobs, housing, and transport; after many years, they may increase the demand for health care and old-age support. At the same time, current working-age groups may form future elderly populations. Long-term planning must therefore project how cohorts will change, not simply describe the population at one date.

Option A is correct because cohort progression links present age groups with future service needs. Option B is too extreme: current percentages can be accurate even though they are insufficient for forecasting. C is the opposite of the demographic reality, and D ignores the importance of age composition. A country with the same total population can face very different future demands depending on the sizes of its children, working-age, and elderly groups.

The ageing index compares the size of the older population with the size of the child population. In the convention used here, it is calculated as \(\frac{\text{population aged 60 and above}}{\text{population aged 0–14}}\times100\). The result indicates how many older persons there are for every 100 children, allowing the age structure of different populations to be compared.

Thus the comparison group is people aged 0–14, making option A correct. The 15–59 group is generally treated as the working-age or adult group and is used in other measures, not this standard ageing-index comparison. A higher index means older people form a larger group relative to children; it does not mean that older people are being compared with half of the total population or only with young adults.

Median age divides a population into two equal-sized groups: approximately half are younger and half are older. If the median age rises steadily, the middle point of the age distribution is moving upward. This indicates that the population is relatively older than before, often because of longer survival, lower fertility or both, although the median alone does not identify the exact cause.

Therefore, option A is the most appropriate conclusion. A rising median age does not prove that birth rates are increasing; increasing births would generally tend to lower the median. It also does not show that the child share is rising, and it clearly indicates that age structure is changing.

A youthful age structure creates population momentum. Even when the average number of children per woman falls, a country may already have a very large group of children and adolescents. As this group grows older, many people enter the reproductive ages at the same time. With more potential parents, the total number of births can remain substantial for a period, even if each person has fewer children than earlier generations. Population growth therefore responds with a delay to falling fertility.

Option A is correct because it identifies the large number of people continuing to enter reproductive ages. Option B is false because mortality does not become zero. Option C is unrelated to the mechanism, and D contradicts the presence of working-age people. Momentum does not mean fertility must rise; it means age structure can keep total population increasing temporarily after fertility declines.

An age pyramid shows the size of different age cohorts. If many people aged 20–29 die during a war, that cohort becomes smaller than the surrounding cohorts. As the survivors of that cohort grow older, the same reduced group appears at older ages in later versions of the pyramid. It therefore produces a notch or narrow section that moves upward over time, although later migration, births, and deaths may alter its exact shape.

Option A is correct because it describes the cohort effect. A population pyramid is not expected to have equal width at every age, so B is unrealistic. A war mortality shock among young adults does not permanently widen only the base, making C incorrect. It also does not affect only newborns, so D does not match the information. The important idea is that an event affecting one cohort can remain visible as that cohort ages.

In the early stage of demographic transition, improvements in health, sanitation and disease control reduce mortality. However, families may continue to have many children because social and economic conditions have not yet changed enough to lower fertility. More children are therefore born, and more of them survive. The population pyramid keeps a broad base, representing a large child and youth population.

Option A is correct because the child and youth share remains large during this stage. Elderly people do not immediately become the majority, since life expectancy has only begun to improve and births remain high. A narrow base would indicate low fertility, while equal age groups are not the expected result of this transition stage.