UPSC 2018 Prelims Questions with Answers

Assumption 1 is valid: the tiger relocated to Panna trekked 250 miles back home, showing relocation between protected areas is not often successful. Assumption 2 is not: the passage attributes tigers living outside reserves to the lack of recognized corridors between habitat islands, not to failed legislation.

The passage says prey and tigers can disperse only if there are recognized corridors of land between protected areas allowing unmolested passage, and that the trek of the relocated tiger highlights this crisis. The logical inference is that safe wildlife corridors between protected areas are an essential aspect of conservation efforts.

The passage condemns the industrial farming model of squeezing animals into cruel, cramped conditions, which has produced pandemics like avian flu, and implies this model of meat production is unsustainable in its environmental cost. It does not demand stopping meat production immediately, only that the environmental cost of industrial meat production is unsustainable.

Neither 1 nor 2 nor 3. The equation x - y = 8 does not force both x and y to be positive; for example x=0, y=-8. If x is positive, y need not be negative; x=10, y=2 works. If x is negative, then y=x-8 is even smaller and cannot be positive. Hence none of the three statements must be true.

1 only. Direct taxes include corporate tax, personal income tax and service tax; their combined share rises sharply over the period. Indirect taxes include excise and customs; their combined share falls. Therefore statement 1 is a logical inference. Statement 2 is not valid because a declining share of excise duty in gross tax revenue does not by itself prove negative growth of manufacturing; it may also reflect tax-policy changes or faster growth of other taxes.

The table only gives GDP growth and tele-density for states at one point in time. It does not establish that high-performing states need further telecom investment to sustain prosperity, nor that very high tele-density is the most essential condition for business and economic growth. Neither assumption is valid.

1 and 3. The table broadly shows that States with higher per capita income tend to have higher tele-density, so statement 1 is a reasonable inference. Statement 2 uses the word always and is contradicted by the table: higher GDP growth does not always correspond to higher per capita income. Statement 3 is valid because high GDP growth does not necessarily produce high tele-density; for example, some States with strong GDP growth have only moderate tele-density.

The graph shows the central bank repeatedly raising the repo and reverse repo rates from July 2010 to June 2011. Raising policy rates is a monetary tightening measure adopted primarily to curb inflation. Hence the most likely reason for the repeated increases is an anti-inflationary stance.

Lakshmi's brother is directly across the net from her daughter. Case 1: the son partners his sister, so the son is diagonally across from the brother; the brother is then the worst player's sibling, making Lakshmi the worst player, and the best player on the same side is the brother. Case 2: the son partners the brother, so the son is diagonally across from the daughter; the daughter is then the worst player's sibling, making the son the worst player, and the best player on the same side is again the brother. In both cases the best player is Lakshmi's brother.

1 and 3 only. In country B, the working-age population rises faster than the dependent groups over the recent decades, so its dependency ratio decreases; statement 1 is valid. By 2050, country A's dependency ratio is not much less than country B's; visually A has a substantial old-age population and a smaller working-age base than B, so statement 2 is not valid. In the next two decades, country B's working-age population continues to rise relative to its total population more favourably than in country A; statement 3 is valid.

Across figures I to VI the square and the triangle each advance one sector per figure in their own fixed directions. Continuing both cycles to stage VII places the square near the top sector and the triangle on the left-lower side.

At 12.5% interest the amount due multiplies by 1.125 each year. Year 1: 22,800 x 1.125 = 25,650; paying 8,650 leaves 17,000. Year 2: 17,000 x 1.125 = 19,125; paying 9,125 leaves 10,000. Year 3: 10,000 x 1.125 = 11,250, which must be paid to clear the debt.

10. Capacity equivalence: 18 adults = 30 children, so 1 adult = 30/18 = 5/3 children. Twelve adults occupy the capacity of 12 x 5/3 = 20 children. Remaining child-capacity = 30 - 20 = 10 children.

The break-even point is where the manufacturing cost (Figure A) equals the projected sales (Figure B); the figures show this point at 2,000 pieces. Below 2,000 pieces the cost exceeds the sales value, so 2,000 is the minimum number of pieces that must be manufactured to avoid a loss.

Each cell of the 3 × 3 matrix combines three features: the bar (straight or curved), the end marker (filled circle, filled square or triangular arrowhead) and the hanging strokes. Reading across each row, the marker type advances in the fixed cycle circle → square → arrowhead, and the bar orientation alternates; reading down each column, the number of hanging strokes increases by one and the bend pattern alternates. Applying the row and column rules to the bottom-right cell gives a filled square at the left end of a horizontal bar with two hanging bent strokes.

The slopes of the graphs are the same. Both figures show the same hourly earnings for the same years: 20, 25, 30, 35 and 40, so the values and the range do not differ. The increase is 5 units per year in both representations, so the slope or rate of increase is the same. Therefore option C is the correct observation.

2 and 4. Population itself has not stabilized merely because birth and death rates are shown; statement 1 is not a logical inference. Population growth rate means the gap between birthrate and death rate. Around 2005 to 2010, that gap becomes nearly stable, so statement 2 is logical. Death rate falls from about 25 to about 20 in the first ten years, which is a fall of about 20 percent, not 10 percent; statement 3 is incorrect. Birthrate also becomes nearly stable after about 35 years, so statement 4 is logical.

Between 1990 and 2010, the gap between the birthrate and the death rate first narrows and then both curves flatten. The population growth rate therefore neither increases nor decreases consistently over the period; it shows no clear trend.

The three wooden blocks must each receive a different colour. The first block can be painted in 6 ways, the second in 5 and the third in 4, giving 6 x 5 x 4 = 120 different ways to paint the winners' stand.

On 1st June, the actual progress is below the expected progress, so option A is correct. The actual line is steepest during August, so option B is correct. The actual work reaches 100 percent at about 1st September, while expected progress is still slightly below 100 percent, so option C is correct. Therefore the statement saying actual progress was at no time more than expected is not correct, because actual progress exceeds expected near the end.

1 sq cm. Let the side of each small square be s. Twelve squares are arranged as 4 columns and 3 rows, so the rectangle dimensions are 4s by 3s. Its diagonal is sqrt((4s)^2 + (3s)^2) = 5s. Given diagonal = 5 cm, s = 1 cm, so area of each square = 1 sq cm.

Each term is 28 days after the previous one: 4/12/95 to 1/1/96, 1/1/96 to 29/1/96, and 29/1/96 to 26/2/96 are all gaps of 28 days. Adding 28 days to 26/2/96 gives 25/3/96, so the next term is 25/3.

8. With 24 equally spaced points, an equilateral triangle is formed by choosing vertices 120 degrees apart. Since 120 degrees corresponds to 24/3 = 8 intervals, starting from each of the 24 points gives the same triangle counted three times. Number of triangles = 24/3 = 8.

Rs. 30. Let cost price be C and profit/loss percentage be p. Selling at 40 gives profit: 40 = C(1+p). Selling at 20 gives equal percentage loss: 20 = C(1-p). Adding the two equations gives 60 = 2C, so C = 30.

The passage warns that monoculture carries great risks - a single disease or pest can wipe out swathes of food production - and that climate change magnifies these risks. The inference is that preserving crop genetic diversity is an insurance against the effects of climate change, not that monoculture is the only way to feed the world.

The passage says we differ in ethnicity, genetics, gender, age, health and lifestyles, and therefore in the foods we tolerate, so such complexities cannot be reduced to a single formula. The essential message is that there is no perfect diet or one solution for obesity.

Assumption 2 is valid: the passage contrasts the old factory-model education suited to the industrial age with today's complex, volatile and globally interconnected world, implying today's learners need new-age skill-sets. Assumptions 1 and 3 are not supported - the passage says nothing about India's development being due to a faulty education system or about Indians studying abroad.

The passage says that under WTO rules India's minimum support prices for agriculture are treated as distorting and subject to limits. Since India uses such price support for food security, the implication is that for India food security collides with trade obligations.

The passage says the Arctic's resources are becoming accessible for longer periods as ice melts, and that unlike Antarctica there is no legal regime protecting it from industrialisation. Melting ice is thus opening a resource and territorial contest - melting of summer ice in the Arctic leads to changes in the geopolitics.

The passage admits science has dangers but opens up the vision of a possible happy world - without poverty, without war, with little illness - and calls science in its very nature a liberator. The author's view is best captured by the idea that a happy world is a dream of science.

The passage links premature deaths from household air pollution to cooking with biomass and coal, with women and children in poor households facing the greatest risk. The inference is that access to clean cooking gas can reduce premature deaths in poor households; it does not claim that rural people are already giving up solid fuels.

Assumption 2 is valid: the passage treats climate change as both a policy and a development issue, more severe for developing countries that must also finance development. Assumption 3 is valid: since funding is vital for adaptation and mitigation, ways and means of finance must be found to enhance adaptive capacity. Assumption 1 is wrong - the passage does not say developed countries face no challenge.

D studies in Assam. The Arts college is in city S (Rajasthan), the Science college is in Kerala and A studies in the Commerce college, so the remaining college for D is Engineering. Hence the Engineering college is located in Assam.

The Arts college is in city S (Rajasthan), the Science college is in Kerala and A studies in the Commerce college. The remaining college is Engineering, and the remaining student D studies in Assam; hence D is studying in the Engineering college.

The Arts college is located in city S which is in Rajasthan, while D is studying in Assam. Since D is in Assam, D cannot be studying in city S, so the statement 'D is not studying in city S' is correct.

D studies in Assam and A studies in the Commerce college. The Science college is in Kerala and the Arts college is in city S (Rajasthan). Hence D must be in the Engineering college (Assam) and the remaining college for C is the Arts college, which is in Rajasthan.

A is in the Commerce college, C is in the Arts college at city S (Rajasthan) and D is in the Engineering college in Assam. The remaining student B must be in the Science college, and B is studying in city Q. Hence the Science college is located in city Q.

A studies in the Commerce college. The Arts college is in Rajasthan (city S), D is in Assam and the Science college is in Kerala. The only remaining State for A is Gujarat.

6. There are 19 boys. 11 wear shirts and 14 wear pants, and nobody is without shirt and/or pants. By inclusion-exclusion, boys wearing both = 11 + 14 - 19 = 6.

He scored 30 marks and failed by 30, so the pass mark is 60. Since 40% of the maximum marks is 60, the maximum marks are 60 x 100/40 = 150.

6:5. B is initially 30 degrees ahead of A. When A reaches the point diametrically opposite its start, A has covered 180 degrees. At that meeting point, B has covered 180 - 30 = 150 degrees. Since both ran for the same time, speed ratio A:B = 180:150 = 6:5.

4/7. Red balls numbered 3 = 40% of 15 = 6. Among black balls, 30% are numbered 3, so black balls numbered 1 or 2 = 70% of 20 = 14. Winning balls = 6 + 14 = 20 out of total 35. Probability = 20/35 = 4/7.

3ax + 8. Total sale = ax + (a+2)(x+2) + (a-2)(x-2). Expanding gives ax + (ax + 2a + 2x + 4) + (ax - 2a - 2x + 4) = 3ax + 8.

Pen < Pencil and Pencil < Book together give Pen < Book by transitivity, whatever the relation between Book and Cap. Hence Pen < Book is always true.

85. Count three-digit numbers from 700 to 999 with hundreds digit greater than tens digit greater than units digit. For hundreds digit 7: choose two smaller digits from 0-6, giving C(7,2)=21. For 8: C(8,2)=28. For 9: C(9,2)=36. Total = 21+28+36 = 85. The number 1000 is not a three-digit number, so it is excluded.

12. A 3 x 3 x 3 painted cube has small cubes with exactly two painted faces along the edges but not at the corners. Each of the 12 edges contributes (3-2)=1 such cube. Total = 12.

2. Let the number be 100a + b because the middle digit is zero. Given a + b = 4. Reversed number = 100b + a, and it is greater by 198: (100b+a) - (100a+b) = 198, so 99(b-a)=198 and b-a=2. Therefore the difference between first and last digits is 2.

The passage rejects the theory that leadership is inborn, stating that the art of leadership can be acquired and can indeed be taught, and that war-time training produces leaders who surprise even the instructors. The essential point is that leadership can be acquired as well as taught.

The passage says the top environmental challenge is people's aspirations, and that we must get beyond the fascination with glitter and treat the planet as a biological system. The message is that reducing our consumerism is very much in our own interest.

Assumption 1 is valid: the passage calls for a diversity of natural assets - crop varieties, breeds, their wild relatives - so that agriculture, forestry and fisheries can cope with climate change, which is diversification as a coping strategy. Assumption 2 is valid: the passage says the private-sector choice of crops favours homogeneity and that wider gene pools of existing crops and wild relatives need conserving, implying monocropping erodes varieties.