CSAT (Paper II): previous-year questions
1280 real UPSC Prelims questions (2011–2026) with the official answer and a clear explanation. 400 of them came in the last five papers.
How often UPSC asks this
Questions per year, counted from the official papers.
Subtopics
Arrangements, ranking, ordering and puzzles
142 questions
Clocks and calendars
5 questions
Coding-decoding, series, patterns, cubes, dice and visual reasoning
110 questions
Communication, interpersonal skills and decision-making
10 questions
Counting, permutations, combinations and probability
1 questions
Directions, blood relations and Venn diagrams
60 questions
General English: grammar, vocabulary and comprehension
20 questions
General Hindi: grammar, vocabulary, dialects and comprehension
25 questions
Geometry and mensuration
26 questions
Number system and basic algebra (divisibility, HCF/LCM, remainders, digits, equations)
196 questions
Percentages, profit and loss, discount, simple and compound interest
47 questions
Ratio, proportion, averages, mixtures and alligation
47 questions
Syllogisms, statements and conclusions, assumptions and arguments
89 questions
Time and work; pipes and cisterns
2 questions
Time, speed and distance; trains, boats and streams; races
48 questions
Attempt the questions
Newest papers first. Tap an option; the answer and the reason appear instantly.
Let A3BC and DE2F be four-digit numbers where each letter represents a different digit greater than 3. If the sum of the numbers is 15902, then what is the difference between the values of A and D?
Answer (c) & explanation
1. Units: C + F ends in 2 and both digits are at least 4, so C + F = 12, carry 1. Tens: B + 2 + 1 ends in 0, so B = 7, carry 1.
2. Hundreds: 3 + E + 1 ends in 9, so E = 5. Thousands: A + D = 15.
3. Digits left (greater than 3, not 5 or 7): C, F = 4, 8 and A, D = 6, 9. Difference = 3.
Answer as per the official UPSC answer key.
The letters from A to Z are numbered from 1 to 26 respectively. If GHI = 1578 and DEF = 912, then what is ABC equal to?
Answer (d) & explanation
ABC equals 246 (d). Step 1: GHI → DEF → ABC: each letter moves back 3 places at each step. So the code should change by the same amount each step. Step 2: 1578 − 912 = 666. Step 3: ABC = 912 − 666 = 246. Options (a), (b) and (c) do not fit.
Tip: if letter groups shift by a fixed step, their codes often shift by a fixed amount too. Find the gap between two known codes and apply it once more.
Answer as per the official UPSC answer key.
A frog tries to come out of a dried well 4·5 m deep with slippery walls. Every time the frog jumps 30 cm, slides down 15 cm. What is the number of jumps required for the frog to come out of the well?
Answer (b) & explanation
The frog needs 29 jumps (b). Step 1: each jump gives a net gain of 30 − 15 = 15 cm. But on the last jump, the frog gets out and does not slide back. Step 2: so before its final jump, the frog must reach 450 − 30 = 420 cm. That takes 420 ÷ 15 = 28 jumps. Step 3: one more jump of 30 cm takes it out: 28 + 1 = 29. Option (c), 30, uses 450 ÷ 15 without the last-jump rule. Options (a) and (d) fail.
Tip: in climbing puzzles, subtract the final full jump from the height first. Then divide the rest by the net gain, and add 1.
450/15 = 30 ignores the last jump, after which it does not slide back.
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Answer as per the official UPSC answer key.
Read the passage
In India, agriculture still engages about half of its workforce, and about 85 per cent of its farms are small and marginal. Compared to China and Vietnam, which have experienced fast structural and rural transformation, India’s story is of slow transformation. As a result, poverty reduction in India was at a much slower pace during 1988–2014, compared to China and Vietnam. India’s poverty reduction was slow during 1988–2005, but during 2005–2012, it accelerated dramatically—almost three times faster than during the earlier period. What did India do during this period? Research reveals that the relative price scenario changed significantly (by more than 50%) in favour of agriculture in the wake of rising global prices. This boosted private investments in agriculture by more than 50%. As a result, agri-GDP growth touched 4·1% during 2007–2012 as against 2·4% during 2002–2007. The net surplus of agri-trade touched $25 billion in 2013–2014; real farm wages rose by 7% per annum. All this led to unprecedented fall in poverty.
Which one of the following statements best reflects the critical message of the passage?
Answer (d) & explanation
The critical message is that inclusive agricultural growth is key to reducing poverty soon (d). Step 1: the passage says faster farm growth, higher wages and a farm trade surplus "led to unprecedented fall in poverty". So farm growth that reaches many people cuts poverty. That is (d). Step 2: option (a), large-scale off-farm jobs, and option (b), farmer producer companies, are not discussed. Step 3: option (c), putting private over public investment, is not the passage's point.
Tip: the critical message ties together the passage's evidence. Here every fact points to farm growth reducing poverty. Pick the option that names that link, not a side topic.
Answer as per the official UPSC answer key.
In a class, there are three groups A, B and C. If one student from group A and two students from group B are shifted to group C, then what happens to the average weight of the students of the class?
Answer (c) & explanation
The class average stays the same (c). Step 1: moving students from groups A and B into group C changes the groups, but not the class. Step 2: the total weight of the class is unchanged, and so is the number of students. Step 3: average = total ÷ number, so the class average stays the same. The group averages may change, but the question asks about the whole class. Options (a), (b) and (d) fail.
Tip: read what the question asks. Shifting people inside a group never changes the overall average. Only adding or removing people from outside can change it.
the groups' averages may change, but the question asks about the class.
Answer as per the official UPSC answer key.
Read the passage
Although most of the Genetically Modified (GM) crops cultivated now are genetically engineered for a single trait, in future, crops genetically engineered for more than one trait will be the norm. Thus, biotechnology’s role in agriculture and the regulation of the same cannot be understood solely in the context of the current generation of GM crops. Instead, there is a need to take a comprehensive look, taking into account various aspects, including socio-economic impacts, so that the potential of the technology can be harnessed while minimizing negative impacts. Given the importance of biotechnology in developing varieties that can help in climate change mitigation and adaptation, not using biotechnology as a part of the climate change action plan cannot be an option. Domestic regulation of biotechnology cannot be viewed in isolation of trade policy and obligations under various international treaties and conventions.
Which one of the following statements best implies the crux of the passage?
Answer (c) & explanation
The crux is that biotechnology's role is not limited to current GM crop priorities (c). Step 1: the passage says its role "cannot be understood solely in the context of the current generation of GM crops". That is (c), almost word for word. Step 2: option (a) is about the precautionary principle, and option (b) about biotech's present use in climate work. Neither is discussed. Step 3: option (d), that negative impacts are not understood, is not the main point.
Tip: the crux is the central claim, often stated directly. When an option repeats a key sentence in plain words, it is usually right. Options that bring in new topics are traps.
Answer as per the official UPSC answer key.
Let x, y be the volumes; m, n be the masses of two metallic cubes P and Q respectively. Each side of Q is two times that of P and mass of Q is two times that of P. Let u = m/x and v = n/y. Which one of the following is correct?
Answer (a) & explanation
u = 4v (a). Step 1: Q's sides are twice P's. Volume grows by the cube: 2 × 2 × 2 = 8. So y = 8x. Step 2: Q's mass is only twice P's: n = 2m. Step 3: v = n ÷ y = 2m ÷ 8x = ¼ × (m ÷ x) = ¼u. So u = 4v. P is four times as dense as Q. Option (b), u = 2v, wrongly doubles the volume instead of multiplying by 8. Options (c) and (d) fail.
Tip: doubling the side multiplies area by 4 and volume by 8. Here u and v are densities (mass ÷ volume). Remember the square and cube rules for scaling.
Doubling the side does not double the volume; it makes it 8 times.
Answer as per the official UPSC answer key.
As a result of 25% hike in the price of rice per kg, a person is able to purchase 6 kg less rice for ₹ 1,200. What was the original price of rice per kg?
Answer (b) & explanation
The original price was ₹ 40 per kg (b). Step 1: a 25% price rise means the same money buys 4/5 as much. So quantity falls by 1/5. Step 2: that 1/5 equals 6 kg. So the old quantity = 6 × 5 = 30 kg. Step 3: old price = 1200 ÷ 30 = ₹ 40. Check: new price = ₹ 50; 1200 ÷ 50 = 24 kg, which is 6 kg less. Options (a), (c) and (d) fail this check.
Tip: price up by 1/4 means quantity down by 1/5 (for fixed spending). Price up by 1/n means quantity down by 1/(n + 1).
Answer as per the official UPSC answer key.
Two Statements S1 and S2 are given below followed by a Question :
S1 : There are not more than two figures on any page of a 51-page book.
S2 : There is at least one figure on every page.
Question : Are there more than 100 figures in that book?
Which one of the following is correct in respect of the above Statements and the Question?
Answer (c) & explanation
S1 and S2 together are not sufficient (c). Step 1: S1 says at most 2 figures per page. S2 says at least 1 figure per page. Step 2: with 51 pages, the total lies between 51 × 1 = 51 and 51 × 2 = 102. Step 3: 102 is above 100, but 51 is not. So the answer could be "yes" or "no". Even together, the statements do not settle it. Options (a), (b) and (d) fail.
Tip: in data sufficiency, find the full possible range. If the range crosses the question's line (here 100), the data are not enough. S1 alone gives 0 to 102; S2 alone gives 51 or more; neither settles it.
Answer as per the official UPSC answer key.
What is the missing term @ in the following?
ACPQ : BESU :: MNGI : @
Answer (d) & explanation
The missing term is NPJM (d). Step 1: find the rule from ACPQ to BESU. A → B (+1), C → E (+2), P → S (+3), Q → U (+4). Step 2: apply it to MNGI. M + 1 = N, N + 2 = P, G + 3 = J, I + 4 = M. Step 3: so the answer is NPJM. Option (a), NPJL, ends with +3 instead of +4. Option (b), NOJM, uses +1 for the second letter. Option (c), NPIL, gets the last two wrong.
Tip: in letter analogies, write the shift for each position. A growing pattern (+1, +2, +3, +4) is very common.
Answer as per the official UPSC answer key.
Two Statements S1 and S2 are given below with regard to four numbers P, Q, R and S followed by a Question :
S1 : R is greater than P as well as Q.
S2 : S is not the largest one.
Question : Among four numbers P, Q, R and S, which one is the largest?
Which one of the following is correct in respect of the above Statements and the Question?
Answer (c) & explanation
S1 and S2 together are sufficient, but neither alone (c). Step 1: S1 says R is greater than P and Q. So the largest is either R or S; we know nothing about S. S1 alone is not enough. Step 2: S2 says S is not the largest. Alone, it leaves P, Q or R, so it is not enough. Step 3: together, S1 rules out P and Q, and S2 rules out S. So R is the largest. Options (a), (b) and (d) fail.
Tip: in data sufficiency, test each statement alone first, then together. Mark what each one rules out. If the two together leave exactly one answer, choose "together sufficient".
Answer as per the official UPSC answer key.
How many different sums can be formed with the denominations ₹ 50, ₹ 100, ₹ 200, ₹ 500 and ₹ 2,000 taking at least three denominations at a time?
Answer (a) & explanation
16 different sums can be formed (a). Step 1: we take at least three notes, each a different denomination. Choose 3 out of 5: 5C3 = 10 ways. Choose 4: 5C4 = 5 ways. Choose all 5: 1 way. Step 2: total = 10 + 5 + 1 = 16. Step 3: no two choices give the same total, because these notes (50, 100, 200, 500, 2000) never add up to each other's sums. So all 16 sums are different. Options (b), (c) and (d) miscount.
Tip: total selections of 5 items = 2⁵ = 32. Minus those with 0, 1 or 2 items (1 + 5 + 10 = 16) gives 16. Both routes agree.
Answer as per the official UPSC answer key.
How many zeroes are there at the end of the following product? 1 × 5 × 10 × 15 × 20 × 25 × 30 × 35 × 40 × 45 × 50 × 55 × 60
Answer (a) & explanation
The product ends in 10 zeros (a). Step 1: each zero needs one 2 and one 5. Step 2: count the 5s. The 12 numbers from 5 to 60 each give one 5. 25 and 50 give one extra each. Total = 14 fives. Step 3: count the 2s. Only the even numbers give 2s: 10 (one), 20 (two), 30 (one), 40 (three), 50 (one), 60 (two). Total = 10 twos. Zeros = the smaller count = 10. Option (c), 14, counts only the 5s. Options (b) and (d) are also wrong.
Tip: usually 2s are plentiful and 5s are scarce. Here most numbers are odd multiples of 5, so the 2s run out first. Always count both.
here the 2s run out first. Counting only the 5s gives 14, which is a trap option.
Answer as per the official UPSC answer key.
The average age of a teacher and three students is 20 years. If all the three students are of same age and the difference between the age of the teacher and each student is 20 years, then what is the age of the teacher?
Answer (c) & explanation
The teacher is 35 years old (c). Step 1: the average of 4 people is 20, so their total = 80 years. Step 2: let each student be s years. The teacher is s + 20. So 3s + (s + 20) = 80, which gives 4s = 60 and s = 15. Step 3: teacher = 15 + 20 = 35 years. Check: 15 + 15 + 15 + 35 = 80. Option (d), 45, and options (a) and (b) fail this check.
Tip: turn the average into a total first (average × number). Then use one letter for the unknown and build a simple equation. Always check by adding back.
Answer as per the official UPSC answer key.
A person X can complete 20% of work in 8 days and another person Y can complete 25% of the same work in 6 days. If they work together, in how many days will 40% of the work be completed?
Answer (a) & explanation
40% of the work takes 6 days (a). Step 1: X does 20% in 8 days, so the full job takes 40 days. Y does 25% in 6 days, so the full job takes 24 days. Step 2: together, per day: 1/40 + 1/24 = 3/120 + 5/120 = 8/120 = 1/15. So together they finish in 15 days. Step 3: 40% of the job takes 0·4 × 15 = 6 days. Option (b), 8, and the others fail.
Tip: convert each person's partial work into full-job time. Then add daily rates (1/days), not days. Using LCM units (here 120 units of work) also makes it quick.
Answer as per the official UPSC answer key.
Consider the following data :
| Average marks in English | Average marks in Hindi | |
|---|---|---|
| Girls | 9 | 8 |
| Boys | 8 | 7 |
| Overall average marks | 8·8 | x |
What is the value of x in the above table?
Answer (a) & explanation
x is 7·8 (a). Step 1: in English, girls average 9 and boys 8. The class average of 8·8 is much nearer 9. So most of the class are girls. Step 2: try 10 students: 8 girls and 2 boys. (8 × 9 + 2 × 8) ÷ 10 = 88 ÷ 10 = 8·8. It fits. So the ratio is 4 : 1. Step 3: Hindi, same class: (8 × 8 + 2 × 7) ÷ 10 = 78 ÷ 10 = 7·8. Options (b), (c) and (d) do not fit this ratio.
Tip: a weighted average sits closer to the bigger group. Use the alligation idea: distances 0·2 and 0·8 give the ratio 4 : 1.
Answer as per the official UPSC answer key.
What is the largest number among the following?
Answer (c) & explanation
(1/3)⁻⁴ is the largest (c). Step 1: a negative power flips the fraction: (1/a)⁻ⁿ = aⁿ. Step 2: so (1/2)⁻⁶ = 2⁶ = 64; (1/4)⁻³ = 4³ = 64; (1/3)⁻⁴ = 3⁴ = 81; (1/6)⁻² = 6² = 36. Step 3: the largest is 81, option (c). Options (a) and (b) tie at 64. Option (d) is the smallest.
Tip: remember x⁻ⁿ = 1/xⁿ. Flipping first turns the question into simple powers. Know powers of 2 up to 2¹⁰ = 1024 and of 3 up to 3⁶ = 729.
Answer as per the official UPSC answer key.
Two Statements S1 and S2 are given below followed by a Question :
S1 : n is a prime number.
S2 : n leaves a remainder of 1 when divided by 4.
Question : If n is a unique natural number between 10 and 20, then what is n?
Which one of the following is correct in respect of the above Statements and the Question?
Answer (d) & explanation
Even together, S1 and S2 are not sufficient (d). Step 1: S1: n is prime and between 10 and 20. That leaves 11, 13, 17 and 19. Not unique. Step 2: S2: n leaves remainder 1 when divided by 4. Between 10 and 20 that gives 13 and 17. Not unique either. Step 3: together, both 13 and 17 are prime and leave remainder 1 (13 = 12 + 1, 17 = 16 + 1). Still two values. So the data are not enough. Options (a), (b) and (c) fail.
Tip: "unique" means exactly one answer. If two values still survive, the statements are insufficient. Listing the candidates is the safest method here.
Answer as per the official UPSC answer key.
Read the passage
Bank credit to the industrial sector has started shrinking. Its decline has been a serious concern as credit growth is essential to revive investment. The problem’s origins lie in the incomplete reforms of the last 25 years. An institutional change that should have followed the 1991 reforms should have been setting up of a resolution corporation for banks. In a market economy with booms and busts, banks should be allowed to be set up and to fail. Today, we cannot shut down banks because there is no proper system to shut them down. Weak loss-making banks continue to need more capital.
Which one of the following is the most logical and rational inference that can be made from the above passage?
Answer (c) & explanation
The inference is that India lacks a system to deal with failed banks (c). Step 1: the passage says "we cannot shut down banks because there is no proper system to shut them down". So India lacks an institutional way to handle bank failure. That is (c). Step 2: options (a) and (b) say banks cannot help growth and that 1991 reforms failed. Both are too sweeping. Step 3: option (d), foreign investment as an alternative, is not discussed.
Tip: when a passage states a problem in one clear line, the inference usually restates it. Note: the Insolvency and Bankruptcy Code, 2016 covers firms; banks still lack a separate resolution law. But answer only from the passage.
Answer as per the official UPSC answer key.
Let XYZ be a three-digit number, where (X + Y + Z) is not a multiple of 3. Then (XYZ + YZX + ZXY) is not divisible by
Answer (b) & explanation
The sum is not divisible by 9 (b). Step 1: in XYZ + YZX + ZXY, each digit appears once in every place (hundreds, tens, units). So the sum = 111X + 111Y + 111Z = 111(X + Y + Z). Step 2: 111 = 3 × 37. So the sum is divisible by 3 (a), by 37 (c) and by (X + Y + Z) (d). Step 3: to be divisible by 9, we need a second factor of 3. That would have to come from X + Y + Z, but the question says it is not a multiple of 3. So the sum is not divisible by 9.
Tip: check with numbers: 124 + 241 + 412 = 777 = 111 × 7. 777 ÷ 9 is not whole.
Answer as per the official UPSC answer key.