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.
If x is greater than or equal to 25 and y is less than or equal to 40, then which one of the following is always correct?
Answer (c) & explanation
(y − x) ≤ 15 is always correct (c). Step 1: y − x is largest when y is as big as possible and x as small as possible: 40 − 25 = 15. So y − x can never be more than 15. Statement (c) always holds. Step 2: check the others. x = 25, y = 40 makes y bigger than x, so (a) fails. It also gives y − x = 15, not greater than 15, so (b) fails. Step 3: a very small y, like y = −100, gives x + y below 65, so (d) fails.
Tip: for "always true" questions with limits, test the extreme values. The edge case (here 25 and 40) usually breaks the wrong options.
Answer as per the official UPSC answer key.
Sunita cuts a sheet of paper into three pieces. Length of first piece is equal to the average of the three single digit odd prime numbers. Length of the second piece is equal to that of the first plus one-third the length of the third. The third piece is as long as the other two pieces together. The length of the original sheet of paper is
Answer (d) & explanation
The sheet is 30 units long (d). Step 1: single-digit odd primes are 3, 5 and 7. Their average is 15 ÷ 3 = 5. So the first piece = 5. Step 2: let the third piece be t. The second piece = 5 + t/3. The third equals the other two together: t = 5 + (5 + t/3), so t − t/3 = 10, giving t = 15. The second piece = 5 + 5 = 10. Step 3: sheet = 5 + 10 + 15 = 30 units. Option (b), 15, is only the third piece. Options (a) and (c) do not fit.
Tip: 2 is the only even prime, so "odd primes" leaves out 2. Shortcut: the third piece is half the sheet, so the sheet is twice 15.
15 is the third piece. The question asks for the whole sheet.
Answer as per the official UPSC answer key.
When a runner was crossing the 12 km mark, she was informed that she had completed only 80% of the race. How many kilometres was the runner supposed to run in this event?
Answer (b) & explanation
The race was 15 km long (b). Step 1: 12 km is 80% of the whole race. Step 2: so the full race = 12 ÷ 0·8 = 12 × 10 ÷ 8 = 15 km. Step 3: check: 80% of 15 = 12. It works. Option (a), 14, and option (c), 16, do not give 12 at 80%. Option (d), 16·5, comes from adding 20% of 12 to 12 plus a little, which is the wrong base.
Tip: if a part and its percentage are given, whole = part ÷ percentage. A common mistake is to add 20% of 12 (giving 14·4); the remaining 20% is of the whole race, not of the part already run.
Answer as per the official UPSC answer key.
What is X in the sequence
132, 129, 124, 117, 106, 93, X?
Answer (c) & explanation
X is 76 (c). Step 1: find the drops: 132 − 129 = 3, 129 − 124 = 5, 124 − 117 = 7, 117 − 106 = 11, 106 − 93 = 13. Step 2: 3, 5, 7, 11, 13 are prime numbers in order. The next prime is 17. Step 3: X = 93 − 17 = 76. Option (b), 75, and option (d), 77, use the wrong drop. Option (a), 74, subtracts 19, skipping a prime.
Tip: when gaps are 2, 3, 5, 7, 11, 13 or similar, think of primes. Note that 9 is skipped because it is not prime. Always write out the differences first in number series.
Answer as per the official UPSC answer key.
Read the following statements S1 and S2 and answer the item that follows :
S1 : Twice the weight of Sohan is less than the weight of Mohan or that of Rohan.
S2 : Twice the weight of Rohan is greater than the weight of Mohan or that of Sohan.
Which one of the following statements is correct ?
Answer (b) & explanation
Sohan's weight is the least (b). Step 1: S1 says 2S < M and 2S < R. Step 2: so S < M/2, which is less than M. And S < R/2, which is less than R. So Sohan is lighter than both Mohan and Rohan. Step 3: therefore Sohan is the lightest. Options (a) and (c) name the wrong person. Option (d) fails because S1 alone fixes the lightest.
Tip: "twice A is less than B" means A is less than half of B, so A is certainly below B. This item and the previous one use the same data: one ordering (least) is fixed, the other (greatest) is not.
Answer as per the official UPSC answer key.
Read the passage
Access to schooling for those coming of school age is close to universal, but access to quality exhibits a sharp gradient with socio-economic status. Quotas for the weaker sections in private schools is a provision introduced by the Right of Children to Free and Compulsory Education Act, 2009. The quotas have imposed a debate on issues of social integration and equity in education that private actors had escaped by and large. The idea of egalitarian education system with equality of opportunity as its primary goal appears to be outside the space that private school principals inhabit. Therefore, the imposition of the quotas has led to resistance, sometimes justified.
With reference to the above passage, the following assumptions have been made :
- 1. Making equality of opportunity a reality is the fundamental goal of the Indian education system.
- 2. The present Indian school system is unable to provide egalitarian education.
- 3. Abolition of private schools and establishment of more government schools is the only way to ensure egalitarian education.
Which of the above assumptions is/are valid ?
Answer (b) & explanation
Only assumption 2 is valid (b). Step 1: the passage says school quality "exhibits a sharp gradient with socio-economic status". In plain words, richer children get better schools. So the present system is not equal. Assumption 2 holds. Step 2: assumption 1 calls equality the fundamental goal of Indian education. The passage notes equality is outside private schools' aims, but it does not show it is the system's core goal. So 1 fails. Step 3: assumption 3 says abolishing private schools is the only way. That is extreme and never argued. Options (a), (c) and (d) fail.
Tip: "abolition" and "only way" are extreme words. Passages describing a problem rarely back such drastic fixes.
Answer as per the official UPSC answer key.
Which year has the same calendar as that of 2009?
Answer (d) & explanation
2015 has the same calendar as 2009 (d). Step 1: two years share a calendar if they start on the same day and are both leap or both non-leap. Step 2: add odd days (days beyond full weeks). A normal year has 1 odd day; a leap year has 2. 2009, 2010 and 2011 give 1 each. 2012 (leap) gives 2. 2013 and 2014 give 1 each. Total = 7 = 0 odd days. Step 3: so 2015 starts on the same day as 2009, and both are non-leap. Options (a), (b) and (c) do not total a multiple of 7.
Tip: a non-leap year's calendar usually repeats after 6 or 11 years. Counting odd days settles it quickly.
Answer as per the official UPSC answer key.
Read the passage
Climate change may actually benefit some plants by lengthening growing seasons and increasing carbon dioxide. Yet other effects of a warmer world, such as more pests, droughts, and flooding, will be less benign. How will the world adapt ? Researchers project that by 2050, suitable croplands for four commodities — maize, potatoes, rice and wheat — will shift, in some cases pushing farmers to plant new crops. Some farmlands may benefit from warming, but others won’t. Climate alone does not dictate yields; political shifts, global demand, and agricultural practices will influence how farms fare in the future.
Which one of the following is the most logical and rational inference that can be made from the above passage ?
Answer (a) & explanation
The inference is that farmers who modernise and diversify will be better placed (a). Step 1: the passage says croplands will shift and "agricultural practices will influence how farms fare". So farmers who adapt their methods and grow varied crops gain. That is (a). Step 2: option (d) calls climate the most important factor. But the passage says "climate alone does not dictate yields". So (d) fails. Step 3: option (b), loss of crop diversity, is not stated. Option (c) predicts a great increase in farmland and output, which the passage never claims.
Tip: when a passage says "X alone does not decide", reject options that make X the main or only factor.
Answer as per the official UPSC answer key.
Ena was born 4 years after her parents' marriage. Her mother is three years younger than her father and 24 years older than Ena, who is 13 years old. At what age did Ena's father get married?
Answer (b) & explanation
Ena's father married at 23 (b). Step 1: Ena is 13. Her mother is 24 years older, so 37. Her father is 3 years older than her mother, so 40. Step 2: Ena was born 4 years after the marriage. So the marriage was 13 + 4 = 17 years ago. Step 3: father's age then = 40 − 17 = 23 years. Option (d), 25, uses the mother's age plus a wrong step. Option (c), 24, confuses the age gap. Option (a) forgets the 3-year difference.
Tip: in age puzzles, first find everyone's present age, then move back in time. Write each step on a line to avoid mixing up who is older.
Answer as per the official UPSC answer key.
In the sequence 1, 5, 7, 3, 5, 7, 4, 3, 5, 7, how many such 5s are there which are not immediately preceded by 3 but are immediately followed by 7 ?
Answer (a) & explanation
Only one 5 fits the rule (a). Step 1: list each 5 with its neighbours. The sequence is 1, 5, 7, 3, 5, 7, 4, 3, 5, 7. First 5: before it is 1, after it is 7. Second 5: before it is 3, after it is 7. Third 5: before it is 3, after it is 7. Step 2: we need a 5 not after 3 but followed by 7. Step 3: the second and third 5s come right after a 3, so they fail. Only the first 5 qualifies. The answer is 1. Options (b), (c) and (d) miscount.
Tip: in such questions, mark each target number and check both sides one by one. Rushing leads to missed or extra counts.
Answer as per the official UPSC answer key.
Raju has ₹ 9000 with him and he wants to buy a mobile handset; but he finds that he has only 75% of the amount required to buy the handset. Therefore, he borrows ₹ 2000 from a friend. Then
Answer (a) & explanation
Raju still does not have enough money (a). Step 1: ₹ 9000 is 75% of the price. So the price = 9000 ÷ 0·75 = ₹ 12,000. Step 2: he borrows ₹ 2000 and now has 9000 + 2000 = ₹ 11,000. Step 3: he is still ₹ 1000 short. So (a) is right. Options (b), (c) and (d) all assume he has enough. They come from working out 25% of 9000 (₹ 2250) instead of 25% of the price.
Tip: the missing 25% is of the price, not of what he has. Find the whole first (part ÷ percentage), then compare.
75% less would be different. Here ₹ 9000 is 75% of the price.
Answer as per the official UPSC answer key.
A wall clock moves 10 minutes fast in every 24 hours. The clock was set right to show the correct time at 8:00 a.m. on Monday. When the clock shows the time 6:00 p.m. on Wednesday, what is the correct time?
Answer (a) & explanation
The correct time is 5:36 p.m. (a). Step 1: the clock gains 10 minutes every 24 hours. So it shows 1450 minutes for every 1440 true minutes. Step 2: from 8:00 a.m. Monday to 6:00 p.m. Wednesday, the clock shows 58 hours = 3480 minutes. True time = 3480 × 1440/1450 = 3456 minutes = 57 hours 36 minutes. Step 3: 8:00 a.m. Monday + 57 h 36 min = 5:36 p.m. Wednesday. Option (b), 5:30 p.m., and the others use the wrong base.
Tip: a fast clock's shown time includes its gain. Convert using the ratio true : shown = 1440 : 1450, not by subtracting a fixed amount.
the clock is fast, so the true time is behind the clock. Adding the 24 minutes instead gives a time not in the options.
Answer as per the official UPSC answer key.
Read the passage
A majority of the TB infected in India are poor and lack sufficient nutrition, suitable housing and have little understanding of prevention. TB then devastates families, makes the poor poorer, particularly affects women and children, and leads to ostracisation and loss of employment. The truth is that even if TB does not kill them, hunger and poverty will. Another truth is that deep-seated stigma, lack of counselling, expensive treatment and lack of adequate support from providers and family, coupled with torturous side-effects demotivate patients to continue treatment — with disastrous health consequences.
Which one of the following is the most logical, rational and crucial message conveyed by the above passage ?
Answer (b) & explanation
The message is that curing TB needs more than diagnosis and medicine (b). Step 1: the passage says nutrition, stigma, counselling and family support all decide whether patients finish their treatment. So medicine alone is not enough. That is (b). Step 2: option (a) says TB is not curable in India. That is extreme; TB is curable with full treatment. Step 3: option (c) blames surveillance, which the passage does not discuss. Option (d) says India will be free of TB only when poverty schemes succeed; "only when" overstates.
Tip: India runs the Ni-kshay Poshan Yojana, which gives TB patients money for nutrition, for exactly this reason. In CSAT, pick the balanced option and drop the extreme ones.
Answer as per the official UPSC answer key.
Number 136 is added to 5B7 and the sum obtained is 7A3, where A and B are integers. It is given that 7A3 is exactly divisible by 3. The only possible value of B is
Answer (d) & explanation
1. Try each value of B in the sum 5B7 + 136.
2. B = 2: 527 + 136 = 663. It must start with 7. Fails. B = 5: 557 + 136 = 693. Fails.
3. B = 7: 577 + 136 = 713. Digit sum 7 + 1 + 3 = 11 is not divisible by 3. Fails.
4. B = 8: 587 + 136 = 723. Digit sum 12 is divisible by 3. Works, so B = 8.
Answer as per the official UPSC answer key.
Read the passage
A bat’s wings may look like sheets of skin. But underneath, a bat has the same five fingers as an orangutan or a human, as well as a wrist connected to the same cluster of wrist bones connected to the same long bones of the arm. What can be more curious than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern ?
Which one of the following is the most logical, scientific and rational inference that can be made from the above passage ?
Answer (d) & explanation
The inference is that man and these animals share an evolutionary history (d). Step 1: the passage says limbs used for very different jobs are "constructed on the same pattern". The same bone plan in a human hand, a bat's wing and a whale's flipper points to a common ancestor. That is (d). Step 2: options (a) and (b) call this biodiversity. But similar structure shows sameness, the opposite of diversity. Step 3: option (c) calls it a coincidence. That is unscientific; such matching patterns are evidence of shared descent.
Tip: these are called homologous organs: same structure, different use. They are classic evidence for evolution in school biology.
Answer as per the official UPSC answer key.
Rakesh had money to buy 8 mobile handsets of a specific company. But the retailer offered very good discount on that particular handset. Rakesh could buy 10 mobile handsets with the amount he had. What was the discount the retailer offered?
Answer (b) & explanation
The discount was 20% (b). Step 1: the same money buys 10 handsets instead of 8. So the new price is 8/10 of the old price. Step 2: the price fell by 2/10 = 20%. Step 3: check with numbers: say the money is ₹ 80,000. Old price = 10,000; new price = 8000. Discount = 2000 ÷ 10,000 = 20%. Option (c), 25%, divides by the new price (2000 ÷ 8000). Options (a) and (d) do not fit.
Tip: a discount is always measured on the original price. Buying 25% more items means a 20% price cut, not 25%. Remember: 1 − 8/10 = 20%.
25% is the rise in quantity, not the fall in price.
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Answer as per the official UPSC answer key.
A joint family consists of seven members A, B, C, D, E, F and G with three females. G is a widow and sister-in-law of D's father F. B and D are siblings and A is daughter of B. C is cousin of B. Who is E ?
- 1. Wife of F
- 2. Grandmother of A
- 3. Aunt of C
Select the correct answer using the code given below :
Answer (d) & explanation
E is F's wife, A's grandmother and C's aunt, so all three are right (d). Step 1: G is a widow and F's sister-in-law, so she is the wife of F's late brother. C, a cousin of B, is G's child. Step 2: there are three females: G, A (B's daughter) and one more. B and D's mother must be in the family, so E is F's wife. Step 3: then E is the grandmother of A, B's daughter. And E is C's aunt, as the wife of C's uncle F. Options (a), (b) and (c) leave out one true link.
Tip: draw a family tree with symbols (+ for male, − for female). Fix the widowed or married pairs first; the rest falls in place.
Answer as per the official UPSC answer key.
In 2002, Meenu's age was one-third of the age of Meera, whereas in 2010, Meenu's age was half the age of Meera. What is Meenu's year of birth?
Answer (b) & explanation
Meenu was born in 1994 (b). Step 1: test the options. Step 2: born 1994: in 2002 Meenu is 8, so Meera is 3 × 8 = 24. In 2010, Meenu is 16 and Meera is 32. 16 is half of 32. It works. Step 3: born 1992: in 2002 Meenu is 10 and Meera 30. In 2010 they are 18 and 38; 18 is not half of 38. So (a) fails. Options (c) and (d) also fail the check.
Tip: algebra works too. Let Meenu be x in 2002, so Meera is 3x. In 2010: 2(x + 8) = 3x + 8, so x = 8. Born 2002 − 8 = 1994. But testing options is often faster in CSAT.
Answer as per the official UPSC answer key.
If the numerator and denominator of a proper fraction are increased by the same positive quantity which is greater than zero, the resulting fraction is
Answer (b) & explanation
The new fraction is always greater than the original (b). Step 1: take a proper fraction a/b, where a < b. Add k to both: (a + k)/(b + k). Step 2: the difference = (a + k)/(b + k) − a/b = k(b − a) / [b(b + k)]. Since b > a and k > 0, this is positive. Step 3: check: 1/2 becomes 2/3 when 1 is added. 2/3 is bigger. So (a), (c) and (d) fail.
Tip: adding the same amount to top and bottom pulls any fraction towards 1. A proper fraction (below 1) rises; an improper fraction (above 1) falls. This one rule answers many CSAT fraction questions instantly.
Answer as per the official UPSC answer key.
A five-storeyed building with floors from I to V is painted using four different colours and only one colour is used to paint a floor.
Consider the following statements :
- 1. The middle three floors are painted in different colours.
- 2. The second (II) and the fourth (IV) floors are painted in different colours.
- 3. The first (I) and the fifth (V) floors are painted red.
To ensure that any two consecutive floors have different colours
Answer (b) & explanation
Statement 3 alone is sufficient (b). Step 1: four colours are used on five floors, so exactly one colour repeats. Step 2: statement 3 says floors I and V are both red. That uses up the one repeat. So floors II, III and IV get the other three colours, all different and none red. Step 3: now every pair of neighbouring floors differs: I (red) and II, II and III, III and IV, IV and V (red). So statement 3 alone is enough. Statements 1 or 2 alone still allow, say, floors I and II to share a colour. So options (a), (c) and (d) fail.
Tip: in sufficiency questions, look for the statement that fixes the one repeat. Once the repeat is placed apart, the rest falls in line.
The key fact is hidden in the first line: four colours on five floors means only one repeat.
Answer as per the official UPSC answer key.