Population Density

A cyclone is a low-pressure system in which air converges toward the centre. In the Southern Hemisphere, the Coriolis effect deflects moving air to the left, producing an overall clockwise circulation around the low-pressure centre. This is opposite to the usual anticlockwise circulation of a cyclone in the Northern Hemisphere. The exact wind pattern may be affected by friction and local conditions, but clockwise is the standard answer.

Population density is a ratio showing the number of people relative to a unit of land area, but it does not describe the quality of life of those people. Two regions may have the same density while differing greatly in average income, employment, housing, sanitation, healthcare, education, transport, natural resources, public services and governance. The distribution of people within each region may also differ, as can inequality and access to facilities. Thus option A is correct. Density remains useful for comparing population pressure, but it is not a complete welfare indicator. The other options are incorrect because density is not always wrong, population conditions do matter, and climate is only one of many influences.

Correct answer: C. A railway can make it faster or less costly to transport farm produce to markets. Better market access may improve farm income and support related jobs and services, which can help retain residents or attract workers. As a result, settlements near stations or agricultural areas may grow. This is a possible indirect effect, not a guaranteed outcome.

Correct answer: A. When climate is similar, differences in human conditions become more important in explaining population attraction. Good schools, hospitals, sanitation, and other services improve quality of life and may attract families, students, workers, and professionals. The area with better services may therefore gain population, although the outcome is not mechanically guaranteed because jobs, housing, and transport also matter. B is contrary to the usual attraction of better facilities. C is wrong because equal climate does not make all social conditions equal. D is absurd because both areas can have population. Memory cue: people choose not only a physical environment but also a quality of life.

Correct answer: D. Housing cost is an important factor in residential location. If central accommodation becomes unaffordable, some households may look for less expensive homes in the suburbs. Good transport connectivity makes suburban living practical because residents can commute to central jobs, schools, and services. Consequently, suburban residential population may increase and the central share may change. A is wrong because high prices do not guarantee rising central density. B is the opposite of the likely effect. C is unrelated: housing prices do not automatically eliminate jobs. Memory cue: affordability plus accessibility encourages suburbanization.

Correct answer: C. Climate and water are important physical conditions for settlement, but people also consider the quality of life offered by a place. Health care is especially important for children, older people, pregnant women, and families needing regular treatment. If medical facilities are poor, some people may avoid moving there, while existing residents may leave when better services are available elsewhere. Option A is wrong because pleasant climate does not remove the need for doctors, hospitals, or medicines. Option B is wrong because water is important but is not the only population factor. Option C is correct because poor services reduce the attractiveness of long-term residence. Option D is wrong because services strongly influence settlement decisions. Memory cue: favourable nature attracts, but adequate services help people stay.

Correct answer: D. A mountain town may depend on roads for visitors, supplies, education, health care, and employment. Tourism supports hotels, restaurants, shops, guiding, transport, and related activities. If access remains blocked, visitors may decline and tourism-based jobs may become less available. Residents, especially workers who cannot find other employment, may move to towns with better opportunities. This is called out-migration and can reduce or redistribute the town’s population. Option A is wrong because loss of jobs does not necessarily increase population. Option B is wrong because road blockage does not immediately change climate. Option C is wrong because tourism is an economic factor that can influence settlement. Option D is correct because reduced accessibility and employment may encourage people to leave. Memory cue: blocked access can weaken economic functions and push people outward.

Correct answer: B. Border towns often depend on the movement of people, goods, vehicles, and services across or near the boundary. Strict restrictions may reduce trade, transport, tourism, markets, and related employment. If economic opportunities become weaker, the town may attract fewer new residents and some existing workers may move elsewhere. Therefore, population growth or concentration can slow down, although the exact outcome depends on the local economy and the duration of restrictions. Option A is wrong because stricter controls do not automatically increase trade. Option B is correct because reduced cross-border activity can weaken employment and settlement attraction. Option C is wrong because political and economic conditions also matter. Option D is wrong because restrictions do not always increase settlement. Memory cue: a border town’s population often reflects the openness of its economic connections.

The correct answer is D. A military base and an airport can bring personnel and create demand for housing, transport, supplies, and other services. These activities may attract residents and lead to a population cluster near the facilities, even if the wider plateau remains sparsely populated. This outcome is possible, not automatic.

Correct answer: D. Mineral deposits may attract mining jobs and related services, but conservation laws can restrict mining, construction, and settlement. If these activities are limited, fewer people may settle near the deposits, so mineral wealth does not necessarily lead to high population concentration.

Population density tells us how many people live, on average, in one unit of land. The standard calculation is \(Population\ density = \frac{Population}{Area}\). Here the population is 180,000 and the area is 900 square kilometres. Dividing gives \(180000 \div 900 = 200\). The unit remains persons per square kilometre because people are being divided by square kilometres.

Therefore, the density is 200 persons per square kilometre, so option C is correct. A quick check also helps: 900 multiplied by 200 equals 180,000. Option A would give only 90,000 people in 900 square kilometres, while the larger values in B and D would imply populations greater than the stated total. The calculation and unit both support C.

Population density tells us how many people live in one unit of area. Therefore, when population and density are known, area is found by dividing population by density. The relationship is (\(Area = \frac{Population}{Density}\)\u0000). This prevents a common mistake: multiplying the two values instead of using the correct rearrangement.

Here, (\(Area = \frac{96000}{120} = 800\)\u0000) square kilometres. The answer is therefore option B. A quick check confirms it: 800 square kilometres with 120 people per square kilometre gives (\(800 \times 120 = 96000\)\u0000) people. The other choices do not satisfy the given population-density relationship.

Population density tells us how many people live in one unit of area. To find total population, multiply density by area: \(P = D \times A\). Here, \(P = 160 \times 450 = 72{,}000\) people. The units also confirm the calculation: persons per square kilometre multiplied by square kilometres leaves persons.

Thus, option C, 72000, is correct. Dividing instead of multiplying would give an incorrect result, and the other numbers do not follow from the given density and area. No conversion is needed because both measurements already use square kilometres.

Population density is calculated as population divided by area: \(D=P/A\). Here the populations of A and B are equal, so the only difference is the denominator. Region A has twice the area of B, meaning the same number of people is spread across twice as much land. Its density is therefore half the density of B. Equivalently, if B has density \(D\), A has \(D/2\).

Option B is correct: region B has twice the density of A. A is not twice as dense, because its larger area spreads the equal population more widely. The two densities cannot be equal unless their areas are equal, and the comparison is possible even without knowing the actual population. Thus the inverse relationship between area and density directly determines the answer.

Density is calculated by dividing population by area: \(D=\frac{P}{A}\). When two regions have exactly the same area, the denominator in this comparison is the same. Their densities therefore change in the same proportion as their populations. If region Y has population \(P\), region X has \(1.25P\), so their densities are \(P/A\) and \(1.25P/A\).

Thus X has a density 1.25 times Y's density, which means it is 25 percent higher. Option A is correct. Equal area does not mean equal density; equal density would require equal population as well. Option D is wrong because a 25 percent population difference does not become a 100 percent difference when the areas are identical.

Density is a ratio of population to area: \(D=\frac{P}{A}\). Suppose the original population is \(P\) and the original area is \(A\). After both rise by 20 percent, the new values are \(1.2P\) and \(1.2A\). Therefore, the new density is \(\frac{1.2P}{1.2A}=\frac{P}{A}\). The same multiplier appears in both numerator and denominator, so it cancels completely.

Option C is correct: density remains the same. For a simple example, 100 people in 10 square kilometres gives 10 people per square kilometre; after a 20 percent rise, 120 people in 12 square kilometres still gives 10. Option A would apply if area did not rise, and option B would require area to grow faster than population. A 40 percent increase, option D, incorrectly adds the two percentage changes instead of comparing their ratio.

Density is the ratio of population to area. When both population and area change, the new density depends on how fast each changes. Here the population becomes 150 percent of its original value, while the area becomes 125 percent of its original value. Since the population grows proportionally more than the area, more people are being placed in each unit of land.

Let the original density be \(P/A\). The new value is \(\frac{1.5P}{1.25A}=1.2\frac{P}{A}\). Thus the density becomes 1.2 times the original, or increases by 20 percent. Therefore option C, density will increase, is correct. It does not remain unchanged because population and area do not rise by the same percentage; it certainly does not become zero.

The correct answer is A: density decreases by 20 percent. Density = population ÷ area. With area fixed, a 20 percent decrease in population makes the quotient—and therefore density—20 percent lower. For example, if the original population is P and area is A, the new density is 0.8P ÷ A, or 80 percent of the original density.

Density equals population divided by area. Let the original values be population \(P\) and area \(A\). A 25 percent fall in area leaves 75 percent of the original area, so the new area is \(0.75A\). Since population is unchanged, the new density is \(\frac{P}{0.75A}=\frac{1}{0.75}\frac{P}{A}=1.333...D\).

The new density is therefore about 133.3 percent of the old density, which means it has increased by about 33.3 percent. Option B is correct. It is not a 25 percent increase, because the denominator has become smaller and the percentage change in a ratio must be calculated from the new area carefully. A fixed population is concentrated into less space.

Density tells us how many people occupy each square kilometre. When density and area are known, total population is found by multiplying them: \(Population=Density\times Area\). In this problem, the calculation is \(320\times250\). Since \(320\times25=8000\), multiplying by ten gives \(320\times250=80000\) persons.

Thus the district has a population of 80,000, so option C is correct. The units also confirm the result: persons per square kilometre multiplied by square kilometres leaves persons. Division would be appropriate for finding density or area, not population in this case. The other choices do not result from the stated multiplication and therefore do not match the given density and area.

Population density is the number of people living in each unit of area. If population and density are known, the area can be found by reversing the density formula. This relationship is useful because population equals density multiplied by area, so area equals population divided by density. The units also confirm that people cancel, leaving square kilometres.

Here, area = population ÷ density = 135000 ÷ 90 = 1500 square kilometres. A quick check gives 90 × 1500 = 135000, so the result is consistent with the given population and density. Therefore, option C is correct. The other values would produce populations different from 135000 at a density of 90 persons per square kilometre.

The correct answer is B, Region Q. Population density = population ÷ area. Region P has a density of 400,000 ÷ 2,000 = 200 persons per square kilometre. Region Q has a density of 300,000 ÷ 1,000 = 300 persons per square kilometre. Since 300 is greater than 200, Region Q is denser.

Arithmetic population density is the ratio of total population to total area, written as D=P/A. If the population increases while the ratio remains unchanged, the denominator must increase in the same proportion. For instance, if population doubles and area also doubles, the quotient remains the same. Thus an expanding administrative boundary or an increase in the measured area could allow total population to rise without changing average density.

Option A describes this mathematically possible situation. If the area shrank, density would normally rise rather than remain stable when population was increasing, so option B is unsuitable. Option C contradicts the statement that population is increasing, and option D is false because area is essential to the density formula. In a real country, area does not usually expand quickly, but the question asks what is possible, including a changed measurement boundary.

Density is a ratio of population to area, so changing the area while holding population constant changes the ratio. If a city’s administrative boundary expands, the measured area becomes larger. The same number of residents is then spread across a larger denominator, so the calculated average density falls. This is a change in the statistical boundary, even if no person moves and the physical settlement pattern remains exactly the same.

Option B is correct. In symbols, with fixed population P, changing area from A to a larger value A' gives \(P/A' < P/A\). Density would increase only if population rose sufficiently while the area expanded, and it would remain unchanged only if population and area rose in the same proportion. Therefore A, C, and D do not follow from the stated conditions.

National arithmetic density is an average found by dividing the total population by the country’s total area. It is useful for comparing countries, but an average does not show where people actually live. A country may contain crowded cities and fertile valleys alongside deserts, mountains, forests, or other nearly empty regions.

When these very different areas are combined into one figure, the high and low densities are smoothed together. The national number may therefore look moderate even though some places are extremely crowded and others are sparsely settled. Option C correctly identifies this limitation. Option A is wrong because density applies to all areas, not only cities; B is wrong because total area is generally known; and D misunderstands the definition, which explicitly includes population.