Population Growth

Correct answer: A. The country with heavy immigration

Correct answer: A, the country with heavy immigration. Total population growth is determined by natural increase plus net migration. Since both countries have the same natural increase, that part contributes equally. Heavy immigration creates positive net migration and adds people to the country, whereas heavy emigration creates negative net migration and removes people. Therefore, all other conditions being equal, the immigration country has the higher total growth rate. B is wrong because emigration lowers total growth. C is wrong because equal natural increase does not mean equal total growth when migration differs. D is wrong because total growth depends on births, deaths, and migration—not on birth rate alone. For example, if both countries have natural growth of 1 percent, immigration of 0.5 percent gives total growth of 1.5 percent, while emigration of 0.5 percent gives 0.5 percent. Memory cue: immigration adds; emigration subtracts.

Correct answer: A. First country

Answer: A, the first country. Percentage growth is calculated as: increase ÷ original population × 100. In the first country, the increase is 8.8 − 8 = 0.8 million, so growth is 0.8 ÷ 8 × 100 = 10%. In the second country, the increase is 84 − 80 = 4 million, so growth is 4 ÷ 80 × 100 = 5%. Thus, the second country adds more people in absolute numbers, but the first country grows faster relative to its original size. A is correct because its relative increase is 10%. B is wrong because 4 million is only the absolute increase, not the percentage growth. C is wrong because 10% and 5% are different. D is wrong because density is not needed; the initial and final populations are sufficient. Memory cue: always divide the increase by the starting population, not the final population.

Correct answer: B. It fell from 15 to 10 per thousand

Answer: B. Natural increase means the birth rate minus the death rate, excluding migration. At first, it is 25 − 10 = 15 per thousand. Later, it is 18 − 8 = 10 per thousand. Therefore, natural increase falls from 15 to 10 per thousand, a decrease of 5 per thousand. A is wrong because 26 is not obtained by subtracting the rates. C reverses the initial and later values. D is wrong because the difference between births and deaths has changed. Notice that both rates decreased, but the birth rate fell by 7 per thousand while the death rate fell by only 2 per thousand. Hence the gap became smaller. Memory cue: natural increase = births minus deaths; do not add the two rates and do not include migration unless total growth is being calculated.

Correct answer: A. The national average can hide regional differences

Answer: A. The national growth rate is an aggregate figure calculated for the whole country. It combines the populations and growth experiences of all provinces, so it is possible for one province to grow by 2.5% while other provinces grow slowly, remain stable, or decline. Their combined result may be only 0.2%. A is correct because an average describes the overall pattern but may conceal important regional variation. B is wrong because a national average does not mean every province has the same rate. C is wrong because provincial populations contribute to the national total; their growth does affect the national figure, even if the effect is weighted by population size. D is wrong because different regional rates do not make the national rate incorrect. Memory cue: an average is a summary, not a mirror of every individual region.

Correct answer: C. 1.21 million

Answer: C. Successive percentage growth is applied to the updated population each year. Start with 1 million. After year one, population = 1 × 1.10 = 1.1 million. During year two, the 10% increase is calculated on 1.1 million, not on the original 1 million: 1.1 × 1.10 = 1.21 million. Therefore, the final population is 1.21 million, or 12.1 lakh. A gives only the first year's result. B incorrectly adds 10% + 10% as a simple 20% increase and ignores compounding. D is too high because two 10% increases do not make a 30% increase. Memory cue: for repeated growth, multiply by the growth factor each time; here it is 1.10 × 1.10.

Correct answer: B. 4 percent decrease

Answer: B. Use a convenient starting population of 100. A 20% increase makes it 100 × 1.20 = 120. The next 20% decrease is calculated on 120, so the decrease is 24 and the final population is 120 − 24 = 96. Compared with the original 100, the final value is 4 lower, which is a 4% decrease. A is wrong because equal percentages do not cancel when they use different bases. C has the wrong direction. D incorrectly applies the 20% decrease to the original population instead of the increased population. The general multiplier is 1.20 × 0.80 = 0.96, confirming that 96% of the original remains. Memory cue: equal percentage rise and fall usually produce a net fall, because the fall acts on the larger intermediate value.

Correct answer: A. -1.1 percent

Answer: A. Total population growth is the sum of natural increase and net migration. Therefore, net migration = total growth − natural increase. Substitute the values: −0.4 − (+0.7) = −1.1%. The negative sign means net out-migration: more people left than entered, when measured as a rate. This out-migration is large enough to overcome the positive natural increase of 0.7%, producing an overall decline of 0.4%. B is wrong because it does not subtract 0.7 correctly. C has the wrong sign and direction. D reverses the subtraction and therefore gives a positive value. Memory cue: total growth = natural increase + net migration; rearrange carefully and preserve the signs, especially when one value is negative.

Correct answer: A. 9.975 million

Answer: A. Begin with 10 million. After a 5% increase, the population becomes 10 × 1.05 = 10.5 million. The following 5% decline is calculated on 10.5 million, not on the original 10 million. The decrease is 10.5 × 0.05 = 0.525 million, leaving 10.5 − 0.525 = 9.975 million. This is 99.75 lakh. A is correct. B is wrong because equal percentage growth and decline do not cancel when applied to different bases. C has the wrong final direction and value. D subtracts 5% from the original population and ignores the preceding increase. The multiplier check is 1.05 × 0.95 = 0.9975, so 99.75% of the original remains. Memory cue: for successive changes, multiply the factors rather than simply adding or subtracting percentages.

Correct answer: B. −0.7%

The correct answer is B: −0.7%. Total population growth equals natural increase plus net migration. Therefore, net migration = total growth − natural increase = 0.9% − 1.6% = −0.7%. The negative rate means that net out-migration reduces the growth that would otherwise result from natural increase.

Correct answer: C. 900,000

The correct answer is C: 900,000 people. To find a one-year increase, convert 1.2 percent into a fraction, 1.2/100, and multiply it by the starting population: 75,000,000 × 1.2/100 = 900,000. Thus, the population would increase by about nine lakh people in one year under the simple calculation. A would result from using 0.8 percent, not 1.2 percent. B incorrectly treats 1 percent as the increase. D treats 1.2 as if it were 1.2 percent of one million or applies the rate incorrectly. The percentage must always be applied to the original population. Memory cue: percentage increase = base population × rate ÷ 100.

Correct answer: C. More than 28 years

The correct answer is C: more than 28 years. The Rule of 70 estimates doubling time as 70 divided by the annual percentage growth rate, assuming that rate stays roughly constant. If the rate declines, population growth slows compared with that assumption, so doubling takes longer than 28 years.

Correct answer: B. 15.5 percent

The correct answer is B: 15.5 percent. The increase is 46.2 − 40 = 6.2 million. Divide this increase by the initial population and multiply by 100: (6.2 ÷ 40) × 100 = 15.5 percent. The initial population is the base for calculating percentage growth.

Correct answer: A. 15 per thousand

The correct answer is A: 15 per thousand. Natural increase is birth rate minus death rate: 33 − 11 = 22 per thousand. Add the net migration rate, keeping its negative sign: 22 + (−7) = 15 per thousand. The negative migration rate reduces the growth rate.

Correct answer: B. −0.8 percent

The correct answer is B: −0.8 percent. Total growth equals natural increase plus net migration, so net migration = total growth − natural increase. Thus, 1.1% − 1.9% = −0.8%. The negative result means net out-migration reduces the growth that would otherwise result from births exceeding deaths.

Correct answer: A. Decrease of 0.2 million

The correct answer is A: a decrease of 0.2 million (200,000 people). Natural increase is 2.2 − 1.3 = 0.9 million. Subtract the 1.1 million net out-migration: 0.9 − 1.1 = −0.2 million. The negative result indicates an overall population decrease.

Correct answer: C. 100 years

The correct answer is C: 100 years. The Rule of 70 is a quick estimate for doubling time: doubling time ≈ 70 ÷ annual growth rate expressed as a percentage. Here, the rate is 0.7 percent, so 70 ÷ 0.7 = 100 years. This means that if the rate remains approximately constant, the population would take about one hundred years to become twice its present size. Option A is wrong because 70 is the numerator of the rule, not the final answer when the rate is 0.7. Option B is wrong because 70 ÷ 0.7 is not 80. Option C is correct because the calculation gives exactly 100. Option D is wrong because it is twice the calculated estimate. The Rule of 70 is only an approximation; changes in birth rate, death rate, or migration can alter the actual time. Memory cue: divide 70 by the percentage rate, not by the decimal 0.007.

Correct answer: A. 0.3 percent increase

The correct answer is A: a 0.3 percent increase. Use an easy starting population of 100. An 18 percent increase adds 18, so the population becomes 118. The next change is a 15 percent decrease from 118, not from the original 100. Fifteen percent of 118 is 17.7, so the final population is 118 − 17.7 = 100.3. Compared with the original 100, this is an increase of 0.3, or 0.3 percent. Option A is therefore correct. Option B is wrong because 2.3 percent does not result from the successive calculation. Option C has the wrong direction: the final value is above 100, not below it. Option D incorrectly subtracts 15 from 18 as if both percentages had the same base; they do not. Memory cue: in successive percentage changes, calculate each percentage on the amount existing at that stage.

Correct answer: C. 4 percent

The correct answer is C: 4 percent. First find the absolute decrease: 45 million − 43.2 million = 1.8 million. Percentage decrease is calculated relative to the initial population, so use the formula: decrease percentage = (decrease ÷ initial population) × 100. Thus, (1.8 ÷ 45) × 100 = 4 percent. Option A is too small and would not represent the given difference. Option B is also incorrect because 1.8 is 4 percent, not 3 percent, of 45. Option C is correct. Option D would imply a decrease of 2.25 million from 45 million, which is larger than the actual decrease of 1.8 million. A common confusion is using the final population, 43.2 million, as the denominator. Percentage decrease normally compares the loss with the starting value, because the question asks how much smaller the population became relative to its original size.

Correct answer: A. Jobs, rental housing, and transport

The correct answer is A: jobs, rental housing, and transport. People aged 22 to 32 are generally young working-age adults. When many such migrants arrive, their immediate needs usually include finding work, securing a place to live, and travelling between home and employment. Therefore, demand for jobs, rented accommodation, public transport, and related urban services is likely to increase first. Option B is not the best answer because elderly care mainly responds to a large older population, whereas the migrants described are young adults. Option C is unsuitable because pensions are associated mainly with retired or elderly people, not with newly arriving working-age migrants. Option D is incorrect because migrants entering a city do not primarily create an immediate demand for agricultural land. Schools and childcare could become more important later if families form or children arrive, but the first direct pressure is usually on employment, housing, and mobility. The word “first” is important: it asks for the most immediate service effects of this age group.

Correct answer: B. 18 percent

The correct answer is B: 18 percent. Percentage population growth is found by comparing the increase with the initial population. First calculate the increase: 64.9 million − 55 million = 9.9 million. Then apply the formula: percentage growth = (increase ÷ initial population) × 100 = (9.9 ÷ 55) × 100 = 18 percent. Option B is therefore correct. Option A would give an increase of only 8.8 million when applied to 55 million, so it is too low. Option C would imply an increase of 11 million, which is greater than the actual 9.9 million. Option D would imply an even larger increase of 12.1 million. Do not use the final population, 64.9 million, as the denominator; the standard percentage change is measured from the starting value. Also distinguish absolute growth, which is 9.9 million, from relative growth, which is 18 percent. Memory cue: subtract first, then divide by the original, then multiply by 100.

Correct answer: A. 5 percent increase

The correct answer is A: a 5 percent increase. Take the initial population as 100. A 40 percent increase makes it 140. The later 25 percent decrease is calculated from 140, so the decrease is 140 × 0.25 = 35. The final population is 140 − 35 = 105. Compared with the initial 100, the final value is 5 higher, which is a 5 percent increase. Option A is correct. Option B is wrong because the final value is above the starting value. Option C incorrectly subtracts 25 from 40 and ignores the change in the base; successive percentages cannot normally be subtracted directly. Option D is wrong because the two changes do not cancel: a 25 percent decrease after a 40 percent increase removes 25 percent of 140, not 25 percent of 100. A useful multiplier method is 1.40 × 0.75 = 1.05, showing that the final amount is 105 percent of the original.

Correct answer: C. 576000

The correct answer is C: 576,000 people. A natural increase rate of 16 per thousand means that, in one year, 16 people are added naturally for every 1,000 people in the population. Convert the rate into a fraction: 16/1000. Then multiply by the population: 36,000,000 × 16/1000 = 576,000. With zero migration, there is no additional increase or decrease from people moving in or out, so the calculated natural increase represents the total population increase under the stated conditions. Option A uses a rate of 10 per thousand and is too low. Option B does not result from multiplying 36 million by 16/1000. Option C is correct. Option D is too high and would correspond to a rate of 20 per thousand. The key distinction is that “per thousand” is not “percent”: divide by 1,000, not by 100.

Correct answer: A. 0.04 percent increase

The correct answer is A: a 0.04 percent increase. Let the initial population be 100. After a 22 percent increase, it becomes 122. The subsequent 18 percent decline is taken from 122, not from 100. Eighteen percent of 122 is 21.96, so the final population is 122 − 21.96 = 100.04. This is 0.04 above the starting value of 100, giving a 0.04 percent increase. Option A is correct. Option B has the wrong direction because the final amount is slightly above the original. Option C incorrectly treats the result as 4 percent by subtracting 18 from 22; that ignores the changed base. Option D has both the wrong direction and the wrong magnitude. The same result can be checked with multipliers: 1.22 × 0.82 = 1.0004, which is 100.04 percent of the initial amount. Memory cue: equal-looking increases and decreases do not cancel unless they are calculated on the same base.