Population Growth

Natural change is found by subtracting the death rate from the birth rate. Here it is \(14-20=-6\) per thousand, meaning there is a natural decrease of 6 per thousand. Net migration is positive at +8 per thousand, so it must be added to the natural change. Total growth is \(-6+8=+2\) per thousand. Therefore option C is correct.

The negative natural change alone would reduce the population, but the inflow of migrants is larger than that reduction. The excess of 2 people per thousand produces positive total growth. Rates must be kept in the same unit, per thousand, before adding them. The answer is not +8 because migration is only one component, and it is not −6 because natural change alone is not total growth.

Total growth is the sum of natural increase and net migration. Therefore, net migration can be isolated by subtracting natural increase from total growth. Both rates use the same unit, per thousand, so no unit conversion is needed before subtraction.

Net migration = total growth − natural increase = \(+4-+13=-9\) per thousand. The negative sign means that more people left than entered, reducing the total growth below the natural increase. Thus option B is correct. A positive 9 per thousand would reverse the subtraction and would make total growth 22 per thousand rather than the stated 4 per thousand.

To find total percentage growth, first calculate the absolute increase and then compare it with the original population. The population rises from 8 million to 9.84 million, so the increase is \(9.84-8.00=1.84\) million, or 1,840,000 people.

Now calculate \(\frac{1.84}{8.00}\times100=23\%\). Therefore option C is correct. The denominator must be the initial population, 8 million, because percentage growth measures change relative to the starting amount. The final population is 123% of the original, so the increase is 23%, not 24% or 23% of the final value.

A constant annual growth rate produces compound growth because each year’s increase is added to the population base for the next year. Starting with 3 million and growing by 5 percent annually for four years gives \(3,000,000\times(1.05)^4\). The factor is raised to the fourth power because the increase occurs four consecutive times.

Since \(1.05^4\approx1.215506\), the final population is approximately 3,646,518, or 3.647 million. In lakh units, this is about 36.47 lakh, so option B is correct. Adding 5 percent four times gives only a rough simple estimate and misses the extra growth on earlier increases. Option D is too high for the stated rate and duration.

Natural increase is calculated by subtracting the death rate from the birth rate. Initially, it is \(36-15=21\) per thousand. After the changes, it becomes \(27-10=17\) per thousand. Although both rates fall, the birth rate falls by 9 per thousand, while the death rate falls by only 5 per thousand, so the gap becomes smaller by 4 per thousand.

Therefore natural increase declines from 21 to 17 per thousand. Option A is correct. It would be wrong to add the rates, because natural increase measures the difference between births and deaths. The change in the death rate partly offsets the fall in the birth rate, which is why the new value is 17 rather than 12 or another listed figure.

People in the reproductive-age group are potential parents, so their number and location affect future births. If many of them leave the country, fewer potential parents remain. Even when the country has a large young population, this out-migration can reduce the number of births occurring within the country.

Therefore option A is the best answer. Fewer births may weaken the future growth created by a youthful age structure, a process called demographic momentum. The effect is not absolutely guaranteed because fertility, return migration, and family patterns also matter, but it is a possible long-term outcome. The other choices use “always,” deny a likely effect, or make an unrelated claim about death rates.

Total population can remain unchanged even when its components are changing. Here natural change is -12,000, meaning deaths exceed births by 12,000. Net migration is +12,000, meaning arrivals exceed departures by the same amount. These two numerical effects cancel, so the total population has no net change.

However, the people represented by these components may belong to different age and work groups. Natural decrease may involve many older residents, while incoming migrants may mainly be young adults of working age. Consequently, the age structure, labour-force composition, skills, and future birth potential can change even though the total count is stable. Thus option A is correct; land area does not automatically increase and births or deaths do not become zero.

A natural increase rate stated per thousand tells how many people are added or lost for every 1,000 members of the population. The rate here is negative, so it represents a natural decrease. To apply the rate, multiply the total population by the rate and divide by 1,000. The answer should retain the negative meaning as a decrease.

The calculation is \(72000000\times(-3.5)\div1000=-252000\). Thus, the population experiences a natural decrease of 252,000 people in one year. Therefore, option C is correct. The result concerns natural change only; migration would need separate information before calculating total population change.

Total population growth combines natural growth and net migration. A negative natural growth means that deaths exceed births, while positive net migration means that more people enter than leave. To find total growth, add the signed values, keeping the negative sign attached to the natural growth figure.

The calculation is \(-0.6+1.4=+0.8\) percent. The positive migration gain of 1.4 percent is larger than the natural decline of 0.6 percent, so the two effects result in an overall increase. Therefore, the total growth rate is positive 0.8 percent and option C is correct. Adding the absolute values would incorrectly produce 2 percent and ignore the opposing signs.

The relationship between the components is total growth = natural increase + net migration. To find net migration, rearrange it as net migration = total growth − natural increase. Keeping the signs is essential because a positive natural increase may be offset by negative migration.

Substituting the values gives \(-0.5-0.9=-1.4\) percent. Thus the net migration rate is negative 1.4 percent, meaning out-migration exceeds immigration by that amount relative to the population. Option A is correct. The negative total growth occurs because this outward migration is larger than the positive natural increase of 0.9 percent. Adding the magnitudes would produce an incorrect result.

A sudden fall in fertility affects births occurring after the change. It does not remove children who were born earlier. Those existing groups continue to grow and reach primary-school age over the following years. Consequently, the number of children entering school does not fall sharply in the same year as the fertility decline. Option A is correct.

School demand usually responds with a time lag. The size of future school-age groups will gradually become smaller if lower fertility continues, but already-born children still require schooling. The exact timing depends on the age structure and school-entry rules. Fertility does affect the future school-age population; therefore option B is incorrect. Schools do not generally increase birth rates, and the change does not make death rates zero.

Age groups are not fixed populations; people move from one age group to the next as time passes. The size of an age group therefore reflects the number of births in earlier years, deaths, and migration. A country can have fewer children today because recent births are lower, while still having many adults because a large group born decades earlier has reached middle adulthood.

Thus, the 30–49 group may be increasing because earlier large cohorts are now entering or moving through those ages. At the same time, low recent fertility makes the 0–14 group smaller. This is why option A is correct. Option B is wrong because age groups need not change in the same direction, and options C and D ignore the connection between birth history and age structure.

Net migration is the difference between the number of people entering and leaving a place. A net value of zero tells us only that these two numbers are equal. It does not mean that the characteristics of the people arriving and departing are identical. Age, education, skills, and other qualities can change the population structure even when the total number remains unchanged.

Here, younger and better-educated arrivals increase the share of people likely to work and add skills to the local population. The departure of older people may further reduce the elderly share. Therefore, human capital and the working-age structure may strengthen, so option A is correct. The total population need not double, natural increase is not automatically zero, and structural effects are possible.

The Rule of 70 is a quick way to estimate how long a population or investment takes to double. It says that doubling time is approximately 70 divided by the annual percentage growth rate. Therefore, when doubling time is known, the growth rate can be found by reversing the operation. The result is expressed as a percentage per year, not as a decimal fraction.

Here the doubling time is 56 years, so the estimated annual growth rate is \(70 \div 56 = 1.25\) percent per year. Thus, option C is correct. Option B, 1 percent, would give a longer doubling time of about 70 years, while 1.5 percent would give a shorter time of about 47 years. The Rule of 70 is approximate, so the answer is an estimate rather than an exact demographic rate.

The Rule of 70 gives a quick estimate of the time needed for a population to double when its annual growth rate remains roughly constant. It uses the number 70 because dividing 70 by the percentage growth rate gives an approximate doubling period in years. A smaller growth rate means that doubling takes longer, while a larger rate means a shorter period.

Here the growth rate is 0.625 percent. Apply the rule: \(70 \div 0.625 = 112\) years. Thus, the estimated doubling time is 112 years, so option C follows. The result is an approximation, not an exact prediction, because real population growth may change due to births, deaths, migration, and changing social conditions.

When percentage increases happen in successive years, the second increase applies to the already enlarged population. Therefore, the percentages should not simply be added unless an approximate, non-compounding estimate is specifically requested. The correct answer is option B, 20.91 percent.

Take an initial population of 100. After a 7 percent increase, it becomes 107. A 13 percent increase on 107 is 13.91, so the final population is 120.91. The total increase is therefore 20.91 percent. In formula form, the multiplier is \(1.07\times1.13=1.2091\). Option A, 20 percent, ignores the extra increase earned on the first year's growth.

Migrants between 20 and 35 are usually in the working-age group. Their arrival can immediately change the age composition by increasing the share of adults who can work. If they obtain jobs, they may also enlarge the number of people earning wages and paying taxes. This can help support public services and reduce, for a time, the pressure created by a large elderly population.

Choice A is correct because it states both likely effects: a higher working-age share and a larger potential tax base. The word “potential” is important, since the result depends on employment, legal status, and tax participation. Choices B and C are too extreme; migration cannot instantly end ageing or remove older people. Choice D is incorrect because migration directly changes population composition.

Total population is the combined number of children, working-age people, and older people. Therefore, the total can continue to rise even when one age group becomes smaller. Population change must be examined by age group, not only by the overall total. A fall in the working-age group can occur alongside growth in other groups.

Option A gives this combination: children and elderly people increase, while working-age adults leave through out-migration. The increase among children and older people can be greater than the loss of working-age adults, so total population still rises. Equal growth in every age group would not explain a decline in the working-age share, and doubling that group would produce the opposite pattern. Thus A is correct.

Demographic momentum means that population growth can continue because of the age structure created in earlier years. When child mortality falls, more of the children already born survive. If families still have many children for some years, the number of surviving young people becomes especially large. This creates a broad young age group, even before fertility begins to decline.

As these surviving children grow up, many will enter the reproductive ages at the same time. Even if each family later chooses fewer children, the large number of potential parents can keep births high for some time. Therefore, option A is correct. Option B is wrong because lower mortality does not make births zero; options C and D ignore the direct effect of a larger surviving cohort.

The total population and the child population have grown at very different rates. Total population increased by 28 percent, whereas the number of children increased by only 2 percent. Thus, children explain only a small part of the overall increase, while other age groups must account for much of it.

The strongest conclusion is that much of the growth came from age groups other than children, so option A follows. Migration of working-age people is one possible reason, although the figures alone do not prove a particular cause. A 28 percent total increase does not mean that births or children also increased by 28 percent. Therefore, options B and C are unsupported, and D is false.

Gross migration counts the total movement into and out of a place. Net migration is different: it is calculated by subtracting out-migration from in-migration. Therefore, a place may receive many migrants and also lose many residents, producing very high gross flows but only a small net change. A small net figure does not mean that movement was unimportant or absent.

For example, if 500,000 people enter and 490,000 leave, the net migration is only 10,000, but nearly one million movements occurred. This shows high population mobility with a small numerical balance. Therefore, option A is the best conclusion. Options B, C, and D confuse a small net difference with small or zero migration in one direction.

A simple one-year increase is found by multiplying the original population by the growth rate written as a decimal. The percentage must first be divided by 100. This calculation gives the number added during one year; it does not include compounding over several years.

The population is 250 million, or 250,000,000 people, and the rate is 0.36 percent. Convert the rate to \(0.0036\), then calculate \(250000000 \times 0.0036 = 900000\). Therefore, 900,000 people are added in one year, making option C correct. The small percentage still produces a substantial number because it is applied to a very large population.

Percentage decrease is always measured against the original, or starting, population. First find how many people were lost by subtracting the final population from the initial population. Then divide that loss by the initial population and multiply by 100. Using the final population as the base would give a different and inappropriate percentage for this question.

The decline is \(62.5-60=2.5\) million people. The percentage decrease is \((2.5 \div 62.5) \times 100 = 4\) percent. Equivalently, using people, \((2500000 \div 62500000)\times100=4\) percent. Therefore, option C, 4 percent, is correct.

Zero net migration describes only the balance between people entering and leaving. It does not mean that the age, sex, skills, or other characteristics of migrants are identical. If mostly young adults enter while mostly elderly people leave, the population can change its age composition even when its total number remains nearly unchanged. The average age may fall, and the proportion of people in the working-age group may rise.

The reasoning is based on replacement by age groups. A 25-year-old entrant usually belongs to the working-age population, whereas a 70-year-old departure removes a person from the elderly group. Thus, the same number entering and leaving can still make the population younger and increase the working-age share. Therefore, option A is correct. The other choices confuse numerical balance with demographic structure.

A falling birth rate means that fewer babies are being added to the population. As younger age groups become smaller, the average or median age rises. However, the total population does not have to stop growing immediately. People already born may continue to live and have children, and low death rates or immigration may add to the population. This combination describes population ageing together with slower growth, not complete stability.

The correct choice is A because all three clues point in the same direction: fertility is declining, the population is still increasing, and the median age is rising. Demographic momentum can keep numbers growing for some time even after births begin to fall. Option B is opposite to the evidence, while C suggests high fertility and a younger population. Option D is incorrect because the total population is still increasing.