CSAT Paper II of the 2018 Preliminary examination, held on 3 June 2018. 80 questions · 200 marks · qualifying at 33%. The questions broke down as Comprehension 35, Basic Numeracy 14, Mental Ability 7, Logical Reasoning 3, Data Interpretation 1.
The answer under each question is UPSC's official key. The note beside it is the first line of our explanation; the full reasoning, option by option, is one click away.
Consider the following sum : • + 1• + 2• + • 3 + • 1 = 21• In the above sum, • stands for
UPSC's answer: (d) — Let • = x, a single digit. Rewrite the terms: • = x, 1• = 10 + x, 2• = 20 + x, •3 = 10x + 3, •1 = 10x + 1, and 21• = 210 + x. Add the left side: x + (10 + x) + (20 + x) + (10x + 3) + (10x + 1) = 23x + 34. Set it equal to the right side: 23x + 34 = 210 + x. Solve: 22x = 176, so x = 8.
Consider the following pattern of numbers : 8 | 10 | 15 | 13 6 | 5 | 7 | 4 4 | 6 | 8 | 8 —————— 6 | 11 | 16 | ? What is the number at ? in the above pattern?
UPSC's answer: (a) — Observe the first column: 8 + 6 + 4 = 18, which is not 6; however, 8 - 6 + 4 = 6, matching the bottom row. Check the second column: 10 - 5 + 6 = 11, which matches the bottom row value. Verify the third column: 15 - 7 + 8 = 16, which matches the bottom row value.
How many diagonals can be drawn by joining the vertices of an octagon?
UPSC's answer: (a) — Each vertex of an n-sided polygon can be joined to n – 3 others by a diagonal (not to itself or its two neighbours), and each diagonal is counted twice. Number of diagonals = n(n – 3) ÷ 2. For an octagon, n = 8: 8 × 5 ÷ 2 = 20, option (a).
A train 200 metres long is moving at the rate of 40 kmph. In how many seconds will it cross a man standing near the railway line?
UPSC's answer: (d) — Convert the train's speed from km/h to m/s by multiplying 40 by 5/18, which equals 100/9 m/s. The distance to be covered to cross a stationary man is equal to the length of the train, which is 200 metres. Calculate the time using the formula Time = Distance / Speed, resulting in 200 / (100/9).
Which of the following is the most logical and rational inference that can be made from the above passage?
UPSC's answer: (a) — The passage highlights that while global population is growing, a disproportionately large share of India's population (47% currently, projected 42% by 2030) depends on agriculture, unlike Europe and North America where only 3-4% are engaged in it.
Which of the following is the most logical corollary to the above passage?
UPSC's answer: (a) — The passage states that rapid globalization of food production increases consumers' vulnerability by making food harder to regulate and trace. It also notes that food contamination can occur at any stage from farm to plate, implying a wider supply chain introduces more potential points of failure.
Which of the following is the most logical and rational inference that can be made from the above passage?
UPSC's answer: (b) — The passage explicitly states that science is used to understand nature but cannot answer fundamental questions like 'Why is there something instead of nothing?'.
The author wants India to rid herself of certain past bonds because
UPSC's answer: (d) — The passage explicitly states the author's desire for India to rid itself of shackles that 'bind and contain her and divide her people'. It further specifies that these shackles 'suppress vast numbers of them' and 'prevent the free development of the body and the spirit'.
According to the passage, which of the following is/are of paramount importance under the Right to Education? 1. Sending of children to school by all parents 2. Provision of adequate physical infrastructure in schools 3. Curricular reforms for developing child-friendly learning system Select the correct answer using the code given below.
UPSC's answer: (c) — The passage states that merely making schooling facilities available (infrastructure) is an 'essential prerequisite' but 'insufficient' to ensure participation, ruling out statement 2 as paramount on its own.
With reference to the above passage, the following assumptions have been made : 1. The Right to Education guarantees teachers' accountability for the learning process of children. 2. The Right to Education guarantees 100% enrolment of children in the schools. 3. The Right to Education intends to take full advantage of demographic dividend. Which of the above assumptions is/are valid?
UPSC's answer: (a) — The passage explicitly states that the Right of Children to Free and Compulsory Education Act lays down that the curriculum should provide for learning through activities, exploration, and discovery, which implies a shift in the teaching-learning process and places obligations on educators…
According to the passage, which one of the following is critical in bringing quality in education?
UPSC's answer: (d) — The passage says quality is an integral part of the right to education, and that the RTE Act requires the curriculum to provide for learning through activities, exploration and discovery.
What is the essential message in this passage?
UPSC's answer: (c) — The passage explicitly states that 'The right to education goes beyond free and compulsory education to include quality education for all.' It argues that merely making schooling facilities available is insufficient; quality is an integral part of the right to education.
If LSJXVC is the code for MUMBAI, the code for DELHI is
UPSC's answer: (a) — The code LSJXVC corresponds to MUMBAI, indicating a pattern where each letter is shifted by a specific number of positions in the alphabet.
If RAMON is written as 12345 and DINESH as 675849, then HAMAM will be written as
UPSC's answer: (b) — From RAMON = 12345, the letter mapping is R=1, A=2, M=3, O=4, N=5. From DINESH = 675849, the letter mapping is D=6, I=7, N=5, E=8, S=4, H=9. Combining these, the specific values for the letters in HAMAM are H=9, A=2, M=3. Substituting these values into HAMAM gives H(9) A(2) M(3) A(2) M(3).
If X is between –3 and –1, and Y is between –1 and 1, then X² – Y² is in between which of the following?
UPSC's answer: (d) — X lies between –3 and –1, so X² lies between 1 and 9. Y lies between –1 and 1, so Y² lies between 0 and 1. X² – Y² is smallest when X² is smallest and Y² is largest (1 – 1 = 0) and largest when X² is largest and Y² is smallest (9 – 0 = 9). Hence X² – Y² lies between 0 and 9, option (d).
X and Y are natural numbers other than 1, and Y is greater than X. Which of the following represents the largest number?
UPSC's answer: (a) — X and Y are natural numbers greater than 1 with Y > X, so X ≥ 2 and Y ≥ 3. X/Y is less than 1, and (X + Y)/XY = 1/X + 1/Y is also less than 1. Y/X is greater than 1, but XY is larger still: XY ÷ (Y/X) = X², which is at least 4. So XY is the largest, option (a).
If E sits in his office and faces the corridor, whose office is to his left?
UPSC's answer: (c) — Take three offices on each side of the corridor, numbered 1 to 3 from the entrance. B and C are on the right; A is on the left, so D (facing C) and F (same side as A) are also on the left, and E is on the right. E has no corner office, so E is in the middle (row 2) on the right.
Who is/are F's immediate neighbour/neighbours?
UPSC's answer: (a) — The arrangement that satisfies all conditions (see the previous item) is: row 1 D (left) and C (right); row 2 A (left) and E (right); row 3 F (left) and B (right). F is in the last office on the left, so its only neighbour on the same side is A in row 2.
According to the passage, which of the following are the consequences of decline in forest cover? 1. Loss of topsoil 2. Loss of smaller rivers 3. Adverse effect on agricultural production 4. Declining of groundwater Select the correct answer using the code given below.
UPSC's answer: (d) — Loss of topsoil (1): the passage says deforestation causes soil and nutrient losses and site degradation through erosive losses. Loss of smaller rivers (2): it attributes the drying up of underground springs and smaller rivers in the Himalaya to drastic changes in forest cover.
Which of the following is/are the correct inference/ inferences that can be made from the passage? 1. Deforestation can cause changes in the course of rivers. 2. Salinization of land takes place due to human activities only. 3. Intense monoculture practice in plains is a major reason for desertification in Tropical Asia, Africa and South America. Select the correct answer using the code given below.
UPSC's answer: (a) — Statement 1 is correct because the passage states that deforestation leads to 'adverse alterations in the hydrology,' which logically includes changes in river courses due to altered water flow and erosion.
With reference to 'desertification', as described in the passage, the following assumptions have been made : 1. Desertification is a phenomenon in tropical areas only. 2. Deforestation invariably leads to floods and desertification. Which of the above assumptions is/are valid?
UPSC's answer: (d) — The passage states that desertification is often linked to arid, semi-arid, and sub-humid ecosystems, but explicitly notes that its impact can be most dramatic in the humid tropics, meaning it is not limited to tropical areas only.
With reference to the above passage, which of the following would assist us in coping with the climate change? 1. Conservation of natural water sources 2. Conservation of wider gene pool 3. Existing crop management practices 4. Migration corridors Select the correct answer using the code given below.
UPSC's answer: (b) — The passage states that relatively intact ecosystems such as forested catchments, mangroves, and wetlands can buffer the impacts of climate change, so conserving natural water sources (1) assists coping.
With reference to the above passage, the following assumptions have been made : 1. Diversification of livelihoods acts as a coping strategy for climate change. 2. Adoption of monocropping practice leads to the extinction of plant varieties and their wild relatives. Which of the above assumptions is/are valid?
UPSC's answer: (c) — The passage states that a diversity of natural assets is needed to cope with climate change, implying that diversification of livelihoods (relying on varied assets) is a valid coping strategy, validating Assumption 1.
Which of the following is the most crucial and logical inference that can be made from the above passage?
UPSC's answer: (c) — The passage identifies the top environmental challenge as a combination of people and their aspirations. It contrasts 'frugal' aspirations (post-WWII) with viewing the planet as a 'giant shopping mall' (consumerism).
The author of the passage holds the view that
UPSC's answer: (b) — The passage explicitly states that the belief that leadership is an innate quality is false. It directly asserts that 'the art of leadership can be acquired and can indeed be taught.' The reference to war is used to illustrate the context in which this discovery is made, not as the sole method of…
A number consists of three digits of which the middle one is zero and their sum is 4. If the number formed by interchanging the first and last digits is greater than the number itself by 198, then the difference between the first and last digits is
UPSC's answer: (b) — Let the number be a0c. Its digits add to 4, so a + c = 4. Interchanging the first and last digits gives c0a, and c0a – a0c = 99(c – a) = 198, so c – a = 2. So the first and last digits differ by 2 (the number is 103 and the new number 301), option (b).
A solid cube of 3 cm side, painted on all its faces, is cut up into small cubes of 1 cm side. How many of the small cubes will have exactly two painted faces?
UPSC's answer: (a) — The 3 cm cube is cut into 3 × 3 × 3 = 27 cubes of 1 cm. Cubes with exactly two painted faces lie on the edges of the big cube but not at its corners. Each of the 12 edges has 3 small cubes: 2 corner cubes and 1 middle cube. So 12 × 1 = 12 small cubes have exactly two painted faces, option (a).
While writing all the numbers from 700 to 1000, how many numbers occur in which the digit at hundred's place is greater than the digit at ten's place, and the digit at ten's place is greater than the digit at unit's place?
UPSC's answer: (c) — The hundreds digit H is 7, 8 or 9 (1000 does not qualify), and we need H > T > U for the tens digit T and units digit U. Any 2 different digits smaller than H give exactly one valid (T, U) pair, so the count is the number of ways of choosing 2 digits from those below H.
If Pen < Pencil, Pencil < Book and Book > Cap, then which one of the following is always true?
UPSC's answer: (b) — The given inequalities are Pen < Pencil, Pencil < Book, and Book > Cap. Combining the first two statements (Pen < Pencil and Pencil < Book) establishes a transitive relationship: Pen < Book.
A bookseller sold 'a' number of Geography textbooks at the rate of ₹ x per book, 'a + 2' number of History textbooks at the rate of ₹ (x + 2) per book and 'a – 2' number of Mathematics textbooks at the rate of ₹ (x – 2) per book. What is his total sale in ₹?
UPSC's answer: (b) — Calculate the revenue from Geography textbooks: a books sold at ₹x each gives a total of ax. Calculate the revenue from History textbooks: (a + 2) books sold at ₹(x + 2) each gives (a + 2)(x + 2) = ax + 2a + 2x + 4.
A bag contains 15 red balls and 20 black balls. Each ball is numbered either 1 or 2 or 3. 20% of the red balls are numbered 1 and 40% of them are numbered 3. Similarly, among the black balls, 45% are numbered 2 and 30% are numbered 3. A boy picks a ball at random. He wins if the ball is red and numbered 3 or if it is black and numbered 1 or 2. What are the chances of his winning?
UPSC's answer: (b) — Total balls = 15 red + 20 black = 35. Red balls numbered 3: 40% of 15 = 6. Black balls numbered 1 or 2: Since 45% are numbered 2 and 30% are numbered 3, the remaining 25% are numbered 1. So, black balls numbered 1 or 2 = 45% + 25% = 70% of 20 = 14. Total winning balls = 6 (Red, No.
Two persons, A and B are running on a circular track. At the start, B is ahead of A and their positions make an angle of 30° at the centre of the circle. When A reaches the point diametrically opposite to his starting point, he meets B. What is the ratio of speeds of A and B, if they are running with uniform speeds?
UPSC's answer: (a) — B starts 30° ahead of A. A runs half the circle (180°) to reach the point diametrically opposite its start. B meets A there, so B has covered 180° – 30° = 150° in the same time. With uniform speeds, speed ratio = distance ratio = 180 : 150 = 6 : 5, option (a).
A student has to get 40% marks to pass in an examination. Suppose he gets 30 marks and fails by 30 marks, then what are the maximum marks in the examination?
UPSC's answer: (c) — The student scored 30 and failed by 30, so the pass mark is 30 + 30 = 60. The pass mark is 40% of the maximum, so maximum = 60 ÷ 0·4 = 150, option (c).
19 boys turn out for playing hockey. Of these, 11 are wearing hockey shirts and 14 are wearing hockey pants. There are no boys without shirts and/or pants. What is the number of boys wearing full uniform?
UPSC's answer: (c) — Total number of boys is 19. Number of boys wearing hockey shirts is 11. Number of boys wearing hockey pants is 14. Using the principle of inclusion-exclusion, the number of boys wearing both shirts and pants (full uniform) is calculated as: (Shirts + Pants) - Total Boys.
A is studying in
UPSC's answer: (b) — Arts college is in city S, Rajasthan (ii), and Science college is in Kerala (v), so Commerce and Engineering are in Gujarat and Assam. D studies in Assam (i).
Science college is located in
UPSC's answer: (a) — From the previous item: A is in Commerce (Gujarat) and D in Engineering (Assam). B studies in city Q (iv). City S has the Arts college, so B is not in Arts; B is therefore in Science, and C in Arts. Science college is thus in B's city, city Q, option (a).
C is studying in
UPSC's answer: (b) — From the earlier items: A is in Commerce (Gujarat), D in Engineering (Assam) and B in Science (Kerala, city Q). The only college left for C is Arts, which is in city S in Rajasthan. So C studies in Rajasthan, option (b).
Which one of the following statements is correct?
UPSC's answer: (a) — From condition (ii), the Arts college is in city S, which is in Rajasthan. From condition (i), D is studying in Assam. Since D is in Assam and city S is in Rajasthan, D cannot be studying in city S.
Which one of the following statements is correct regarding Engineering college?
UPSC's answer: (d) — From constraint (ii), Arts college is in city S, Rajasthan; from (v), Science college is in Kerala. This leaves Commerce and Engineering to be placed in Gujarat and Assam. Constraint (i) states D is studying in Assam, so D's college must be the one located in Assam.
Which one of the following statements is correct?
UPSC's answer: (a) — From (ii), Arts college is in city S, which is in Rajasthan. From (v), Science college is in Kerala. From (i), D is studying in Assam. Since Arts is in Rajasthan and Science is in Kerala, D cannot be in Arts or Science colleges. From (iii), A is in Commerce college.
With reference to the above passage, the following assumptions have been made : 1. Climate change is not a challenge for developed countries. 2. Climate change is a complex policy issue and also a development issue for many countries. 3. Ways and means of finance must be found to enable developing countries to enhance their adaptive capacity. Which of the above assumptions is/are valid?
UPSC's answer: (c) — Assumption 1 is invalid because the passage states that 'Most countries' treat climate change as a real threat, implying it is a challenge for both developed and developing nations, not just the latter.
Which of the following is the most crucial and logical inference that can be made from the above passage?
UPSC's answer: (d) — The passage states that over 10 lakh premature deaths occur annually from household air pollution caused by polluting cooking fuels, with women and children in poor populations facing the greatest risk.
Which one of the following is the most important implication of the passage?
UPSC's answer: (a) — The passage states that scientific knowledge 'opens up as nothing else can, the vision of a possible happy world'. This phrasing indicates that science provides the conceptual framework or 'vision' for a world without poverty, war, and illness.
Which one of the following is the most important implication of the passage?
UPSC's answer: (b) — The passage highlights that the Arctic's fossil fuel, fish, and mineral reserves are becoming accessible for a longer period due to melting ice.
What is the crucial message conveyed by the above passage?
UPSC's answer: (c) — The passage states that India is bound by WTO agreements, specifically Article 6 of the Agriculture Agreement, which limits agricultural subsidies to 10% of production value for developing countries.
With reference to the above passage, the following assumptions have been made : 1. India continues to be a developing country essentially due to its faulty education system. 2. Today's learners need to acquire new-age skill-sets. 3. A good number of Indians go to some developed countries for education because the educational systems there are a perfect reflection of the societies in which they function. Which of the above assumptions is/are valid?
UPSC's answer: (b) — The passage states that the current educational system is designed for the industrial age to produce compliant workers with narrow capabilities, which no longer suits the complex, volatile, and globally interconnected world of today.
What is the most logical and rational inference that can be made from the above passage?
UPSC's answer: (d) — The passage explicitly states that due to individual differences in genetics, ethnicity, and health status, 'we really cannot reduce so many complexities into one diet or diet book.' It argues that the failure of diets globally is because they do not address the specific, underlying reasons for…
Which of the following is the most logical, rational and crucial message given by the passage?
UPSC's answer: (a) — The passage opens by stating that monoculture carries great risks because a single disease or pest can wipe out large portions of food production.
A shopkeeper sells an article at ₹ 40 and gets X% profit. However, when he sells it at ₹ 20, he faces same percentage of loss. What is the original cost of the article?
UPSC's answer: (c) — Let the cost price (CP) be C and the profit/loss percentage be X%. Selling at ₹40 gives a profit of X%, so 40 = C(1 + X/100). Selling at ₹20 gives a loss of X%, so 20 = C(1 - X/100). Adding the two equations: 40 + 20 = C(1 + X/100) + C(1 - X/100). This simplifies to 60 = 2C, which means C = 30.
There are 24 equally spaced points lying on the circumference of a circle. What is the maximum number of equilateral triangles that can be drawn by taking sets of three points as the vertices?
UPSC's answer: (c) — The 24 points are equally spaced, so the central angle between adjacent points is 360°/24 = 15°. An equilateral triangle inscribed in a circle must have its vertices separated by arcs of 120° each (since 360°/3 = 120°).
Consider the sequence given below : 4/12/95, 1/1/96, 29/1/96, 26/2/96, .... What is the next term of the series?
UPSC's answer: (b) — The sequence represents dates in DD/MM/YY format: 4/12/95, 1/1/96, 29/1/96, 26/2/96. Calculate the number of days between consecutive terms: From 4/12/95 to 1/1/96 is 28 days (27 days remaining in Dec 95 + 1 day in Jan 96). From 1/1/96 to 29/1/96 is 28 days.
Twelve equal squares are placed to fit in a rectangle of diagonal 5 cm. There are three rows containing four squares each. No gaps are left between adjacent squares. What is the area of each square?
UPSC's answer: (c) — Let each square have side s cm. Three rows of four squares make a rectangle 4s long and 3s wide. Its diagonal is 5 cm, so (4s)² + (3s)² = 5², that is 16s² + 9s² = 25, giving 25s² = 25. So s² = 1: each square has an area of 1 sq cm, option (c).
A lift has the capacity of 18 adults or 30 children. How many children can board the lift with 12 adults?
UPSC's answer: (b) — The lift's full capacity is stated as 18 adults or 30 children, meaning the total weight of 18 adults equals the total weight of 30 children. From this, the weight of one adult equals 30/18 = 5/3 children. Twelve adults therefore occupy a weight equivalent to 12 × (5/3) = 60/3 = 20 children.
A person bought a refrigerator worth ₹ 22,800 with 12·5% interest compounded yearly. At the end of first year he paid ₹ 8,650 and at the end of second year ₹ 9,125. How much will he have to pay at the end of third year to clear the debt?
UPSC's answer: (d) — The initial debt of ₹ 22,800 accrues 12.5% interest, resulting in a balance of ₹ 25,650 at the end of the first year. After the payment of ₹ 8,650, the remaining principal for the second year is ₹ 17,000.
With reference to the above table, which of the following is/are the most logical and rational inference/inferences that can be made? 1. Higher per capita income is generally associated with higher Tele-density. 2. Higher GDP growth rate always ensures higher per capita income. 3. Higher GDP growth rate does not necessarily ensure higher Tele-density. Select the correct answer using the code given below.
UPSC's answer: (c) — Statement 1 holds as a general pattern: most high-income states have high tele-density (State 7: income 900, tele-density 104·86; State 10: income 893, tele-density 96·7; State 14: income 864, tele-density 97·9), while most low-income states have low tele-density (State 11: income 363, tele-density…
With reference to the above table, the following assumptions have been made : 1. Nowadays, prosperity of an already high performing State cannot be sustained without making further large investments in its telecom infrastructure. 2. Nowadays, a very high Tele-density is the most essential condition for promoting the business and economic growth in a State. Which of the above assumptions is/are valid?
UPSC's answer: (d) — Assumption 1 claims that high-performing states cannot sustain prosperity without further large telecom investments, but the table shows State 7 with the highest tele-density (104.86) has a lower GDP growth rate (8.88%) than State 6 (77.5 tele-density, 11.69% growth), disproving the necessity of…
If x – y = 8, then which of the following must be true? 1. Both x and y must be positive for any value of x and y. 2. If x is positive, y must be negative for any value of x and y. 3. If x is negative, y must be positive for any value of x and y. Select the correct answer using the code given below.
UPSC's answer: (d) — Statement 1 is false because x and y can both be negative (e.g., x = -1, y = -9) or both positive (e.g., x = 10, y = 2), so they are not required to be positive.
What is the most rational and crucial message given by the passage?
UPSC's answer: (d) — The passage highlights three main issues with factory farming: animal cruelty, health pandemics, and high water consumption. It provides specific data comparing water usage: 15,000 litres per kg of meat versus 3,400 litres for rice, 3,300 for eggs, and 255 for potatoes.
Which of the following is the most rational and crucial message given by the passage?
UPSC's answer: (b) — The passage describes a tiger trekking 250 miles from Panna National Park to Pench Tiger Reserve, illustrating the need for movement between isolated habitats.
With reference to the above passage, the following assumptions have been made : 1. The strategy of conservation of wildlife by relocating them from one protected area to another is not often successful. 2. India does not have suitable legislation to save the tigers, and its conservation efforts have failed which forced the tigers to live outside protected areas. Which of the above assumptions is/are valid?
UPSC's answer: (a) — The passage states that a tiger relocated from Pench to Panna trekked 250 miles back to its home, indicating that this specific relocation strategy failed to retain the animal in the new protected area.
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