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.
There are two Classes A and B having 25 and 30 students respectively. In Class-A the highest score is 21 and lowest score is 17. In Class-B the highest score is 30 and lowest score is 22. Four students are shifted from Class-A to Class-B. Consider the following statements :
- 1. The average score of Class-B will definitely decrease.
- 2. The average score of Class-A will definitely increase.
Which of the above statements is/are correct ?
Answer (a) & explanation
Only statement 1 is correct (a). Step 1: every student in Class A scores between 17 and 21. Every student in Class B scores 22 or more. Step 2: the four new students in B all score less than anyone already in B. So B's average must fall (statement 1). Step 3: Class A's average depends on who leaves. If the four toppers leave, A's average falls. If the four lowest leave, it rises. So it does not "definitely" increase (statement 2 fails). Options (b), (c) and (d) fail.
Tip: adding values below the average always lowers it. Removing values changes the average only according to which ones are removed; "definitely" needs every case to agree.
the word "definitely". 2 can happen, but it does not have to.
UPSC repeats traps like this year after year. The PYQ Book gathers every trap in one place, so you see them coming. Try the free sample
Answer as per the official UPSC answer key.
There are 6 persons arranged in a row. Another person has to shake hands with 3 of them so that he should not shake hands with two consecutive persons. In how many distinct possible combinations can the handshakes take place ?
Answer (b) & explanation
There are 4 ways (b). Step 1: number the people 1 to 6 in the row. We must choose 3 of them, with no two standing side by side. Step 2: list the choices: (1, 3, 5), (1, 3, 6), (1, 4, 6) and (2, 4, 6). Step 3: that is 4 ways. Options (a) 3, (c) 5 and (d) 6 miss or add cases.
Tip: a quick formula for choosing k items from n in a row with no two adjacent is C(n − k + 1, k). Here C(4, 3) = 4.
Answer as per the official UPSC answer key.
A boy plays with a ball and he drops it from a height of 1·5 m. Every time the ball hits the ground, it bounces back to attain a height 4/5th of the previous height. The ball does not bounce further if the previous height is less than 50 cm. What is the number of times the ball hits the ground before the ball stops bouncing ?
Answer (b) & explanation
The ball hits the ground 5 times (b). Step 1: each bounce reaches 4/5 of the previous height. It starts at 150 cm. Step 2: hit 1 → rises to 120 cm. Hit 2 → 96 cm. Hit 3 → about 77 cm. Hit 4 → about 61 cm. Hit 5 → about 49 cm. Step 3: after the fifth hit, the height is below 50 cm, so it does not bounce again. The ball hits the ground 5 times. Option (a), 4, stops too early. Options (c) and (d) go too far.
Tip: list each step in a small table. Converting metres to centimetres first (1·5 m = 150 cm) avoids decimal errors.
Some readers count one more landing after the last small bounce; the official answer is (b), as printed.
Answer as per the official UPSC answer key.
Which day is 10th October, 2027 ?
Answer (a) & explanation
10 October 2027 is a Sunday (a). Step 1: use an anchor date: 10 October 2021 was a Sunday (the CSAT exam was held that day). Step 2: count odd days from 10 Oct 2021 to 10 Oct 2027. That is 6 years, and each normal year adds 1 odd day. Only one 29 February falls in between (2024), adding 1 more. Total = 6 + 1 = 7 odd days = 0 extra. Step 3: so the weekday stays the same: Sunday. Options (b), (c) and (d) come from missing or adding the leap day.
Tip: a normal year shifts the weekday by 1, a leap year by 2. Count only the 29 Februarys that fall inside your range.
Answer as per the official UPSC answer key.
A man completes 7/8 of a job in 21 days. How many more days will it take him to finish the job if quantum of work is further increased by 50% ?
Answer (d) & explanation
He needs 15 more days (d). Step 1: he does 7/8 of the job in 21 days. So the whole job takes 21 ÷ 7/8 = 24 days. Step 2: the work is raised by 50%, so the total is now 1.5 jobs. Work left = 1.5 − 7/8 = 12/8 − 7/8 = 5/8 of a job. Step 3: 5/8 of a job takes 5/8 × 24 = 15 days. Option (a), 24, is the time for one full job. Options (b) and (c) miscalculate the remaining work.
Tip: first find the time for one full job. Then any amount of work is just that fraction of the time.
the 50% is added to the whole job, not to the remaining 1/8.
Fell for this one? Most aspirants do. The PYQ Book puts every UPSC trap side by side, so the pattern finally clicks. Try the free sample
Answer as per the official UPSC answer key.
| 7B | 10A | 3C |
|---|---|---|
| 3C | 9B | 6A |
| 10A | 13C | ? |
Following is a matrix of certain entries. The entries follow a certain trend row-wise. Choose the missing entry (?) accordingly.
Answer (c) & explanation
The missing entry is 3B (c). Step 1: look at the numbers in each row. The third number is the second minus the first: 10 − 7 = 3 and 9 − 3 = 6. So in the last row, 13 − 10 = 3. Step 2: look at the letters. Each row uses A, B and C once each. The last row already has A and C, so the missing letter is B. Step 3: put them together: 3B. Option (a), 9B, gets the number wrong. Options (b) 3A and (d) 3C repeat a letter already in the row.
Tip: in matrix puzzles, split the entry into parts (number and letter) and solve each part on its own. Check your rule on every row before trusting it.
Answer as per the official UPSC answer key.
Consider the following addition problem : 3P + 4P + PP + PP = RQ2; where P, Q and R are different digits. What is the arithmetic mean of all such possible sums ?
Answer (c) & explanation
The mean of the possible sums is 202 (c). Step 1: write out the sum: 3P + 4P + PP + PP = (30 + P) + (40 + P) + 11P + 11P = 70 + 24P. Step 2: the sum RQ2 ends in 2. So 24P must end in 2, which happens when P = 3 (sum 142) or P = 8 (sum 262). In both, P, Q and R are different digits. Step 3: the mean is (142 + 262) ÷ 2 = 202. Options (a), (b) and (d) do not match.
Tip: in digit puzzles, start with the units place. The last digit of a sum usually narrows the choices to one or two.
Answer as per the official UPSC answer key.
The number 3798125P369 is divisible by 7. What is the value of the digit P ?
Answer (b) & explanation
P is 6 (b). Step 1: a test for 7 (it also works for 11 and 13): from the right, split the number into groups of three digits and add and subtract them in turn. 3798125P369 splits into 37 | 981 | 25P | 369. Step 2: 369 − 25P + 981 − 37 = 1313 − (250 + P) = 1063 − P. This must be divisible by 7. Step 3: 1063 = 7 × 151 + 6. So 1063 − P is divisible by 7 when P = 6. Options (a), (c) and (d) leave remainders.
Tip: the alternating three-digit sum works because 1001 = 7 × 11 × 13. It is the fastest check for large numbers.
Answer as per the official UPSC answer key.
Consider two Statements and a Question :
Statement-1 : Priya is 4 ranks below Seema and is 31st from the bottom.
Statement-2 : Ena is 2 ranks above Seema and is 37th from the bottom.
Question : What is Seema's rank from the top in the class of 40 students ?
Which one of the following is correct in respect of the Statements and the Question ?
Answer (c) & explanation
Either statement alone is enough (c). Step 1: in a class of 40, rank from top = 40 − rank from bottom + 1. Step 2: Statement-1: Priya is 31st from the bottom, so she is 40 − 31 + 1 = 10th from the top. Seema is 4 ranks above her, so 6th. Step 3: Statement-2: Ena is 37th from the bottom, so 4th from the top. Seema is 2 ranks below her, so again 6th. Each statement alone gives the answer. Options (a) and (b) wrongly say one is not enough. Option (d) wrongly says both are needed.
Tip: in data sufficiency, test each statement on its own first. Only combine them if neither works alone.
Answer as per the official UPSC answer key.
An amount of money was distributed among A, B and C in the ratio p : q : r. Consider the following statements :
- 1. A gets the maximum share if p is greater than (q + r).
- 2. C gets the minimum share if r is less than (p + q).
Which of the above statements is/are correct ?
Answer (a) & explanation
Only statement 1 is correct (a). Step 1: if p is greater than q + r, then p is more than half the total. So p is bigger than both q and r, and A gets the maximum share. Statement 1 is true. Step 2: r less than p + q only means r is less than half. That does not make r the smallest. Step 3: try 1 : 5 : 4. Here r = 4 is less than 6, but A gets the least, not C. So statement 2 is false, and options (b), (c) and (d) fail.
Tip: to disprove a "general" statement, find one counter-example with small numbers.
Answer as per the official UPSC answer key.
Images of consonants of the English alphabet (Capitals) are observed in a mirror. What is the number of images of these which do not look like their original shapes ?
Answer (b) & explanation
14 consonants look different in a mirror (b). Step 1: a capital letter looks the same in a mirror if it has a vertical line of symmetry. Step 2: among the 21 consonants, these have one: H, M, T, V, W, X, Y. That is 7 letters. Step 3: the rest look different: 21 − 7 = 14. Option (a), 13, wrongly includes another letter. Options (c) and (d) miss some symmetric letters.
Tip: the vowels A, I, O and U are also symmetric, but the question asks only about consonants. There are 26 letters, 5 vowels, so 21 consonants. Memorise "AHIMOTUVWXY" as the mirror-same capitals.
Answer as per the official UPSC answer key.
Consider two Statements and four Conclusions given below. You have to take the Statements to be true even if they seem to be at variance from the commonly known facts. Read all Conclusions and then decide which of the given Conclusion(s) logically follows/follow from the Statements, disregarding the commonly known facts.
Statement-1 : Some greens are blues.
Statement-2 : Some blues are blacks.
Conclusion-1 : Some greens are blacks.
Conclusion-2 : No green is black.
Conclusion-3 : All greens are blacks.
Conclusion-4 : All blacks are greens.
Which one of the following is correct ?
Answer (d) & explanation
None of the four conclusions follows (d). Step 1: "some greens are blues" and "some blues are blacks" give no sure link between greens and blacks. The blues that are black may not be the green ones. Step 2: so "some greens are blacks" (1), "no green is black" (2), "all greens are blacks" (3) and "all blacks are greens" (4) are each possible, but none is certain. Step 3: options (a), (b) and (c) pair conclusions that do not follow. Conclusions 1 and 2 do form an "either-or" pair, but no option offers "either 1 or 2".
Tip: two "some" statements never give a definite conclusion. Draw the circles in two ways; if the answer changes, nothing follows.
1 and 2 form an 'either–or' pair, but no option offers 'either 1 or 2'.
UPSC repeats traps like this year after year. The PYQ Book gathers every trap in one place, so you see them coming. Try the free sample
Answer as per the official UPSC answer key.
You are given two identical sequences in two rows :
| Sequence-I : | 8 | 4 | 6 | 15 | 52.5 | 236.25 |
|---|---|---|---|---|---|---|
| Sequence-II : | 5 | A | B | C | D | E |
What is the entry in the place of C for the Sequence-II ?
Answer (c) & explanation
The entry at C is 9.375 (c). Step 1: find the rule in Sequence-I. Each term is the one before multiplied by 0.5, 1.5, 2.5, 3.5, 4.5 in turn. The multiplier grows by 1 each step. Step 2: the two sequences are "identical", so Sequence-II follows the same rule, only starting from 5. Step 3: 5 × 0.5 = 2.5, then 2.5 × 1.5 = 3.75, then 3.75 × 2.5 = 9.375. Option (a), 2.5, is the first step and option (b), 5, is the start. Option (d), 32.8125, is a later term.
Tip: when a sequence grows unevenly, divide each term by the one before it. The pattern often hides in these ratios.
Answer as per the official UPSC answer key.
Consider the following multiplication problem :
(PQ) × 3 = RQQ, where P, Q and R are different digits and R ≠ 0.
What is the value of (P + R) ÷ Q ?
Answer (b) & explanation
(P + R) ÷ Q is 2 (b). Step 1: Q × 3 must end in Q. Only Q = 0 (0 × 3 = 0) and Q = 5 (5 × 3 = 15) work. Step 2: if Q = 0, then P0 × 3 = R00, which no single digit P can give. So Q = 5. Step 3: try P5 × 3 until the result ends in 55: 85 × 3 = 255. So P = 8 and R = 2. Then (P + R) ÷ Q = 10 ÷ 5 = 2. Option (d) is wrong because the data do fix the answer.
Tip: look for digits that repeat themselves when multiplied (0, 1, 5, 6). They often unlock such puzzles quickly.
Answer as per the official UPSC answer key.
From January 1, 2021, the price of petrol (in Rupees per litre) on mth day of the year is 80 + 0·1m, where m = 1, 2, 3, ..., 100 and thereafter remains constant. On the other hand, the price of diesel (in Rupees per litre) on nth day of 2021 is 69 + 0·15n for any n. On which date in the year 2021 are the prices of these two fuels equal ?
Answer (b) & explanation
The prices are equal on 20th May (b). Step 1: in the first 100 days, petrol = 80 + 0·1m and diesel = 69 + 0·15n. Setting them equal gives 0·05n = 11, so n = 220. That is outside the first 100 days, so there is no match there. Step 2: after day 100, petrol stays at 80 + 10 = ₹ 90. Diesel = 90 when 69 + 0·15n = 90, so n = 140. Step 3: day 140 of 2021: January to April = 31 + 28 + 31 + 30 = 120 days. Day 140 is the 20th of May. Options (a), (c) and (d) are off by a day.
Tip: always check the range where a formula applies. 2021 is not a leap year, so February has 28 days.
the petrol formula stops at day 100. Using it beyond that gives a wrong day.
Answer as per the official UPSC answer key.
Consider two Statements and a Question :
Statement-1 : Each of A and D is heavier than each of B, E and F, but none of them is the heaviest.
Statement-2 : A is heavier than D, but is lighter than C.
Question : Who is the heaviest among A, B, C, D and E ?
Which one of the following is correct in respect of the Statements and the Question ?
Answer (c) & explanation
1. Statement-1 alone: A and D beat B, E and F, but we are not told who beats A and D. C is never mentioned, so we cannot name the heaviest.
2. Statement-2 alone: C > A > D. We know nothing about B and E, so again we cannot say.
3. Together: C > A > D, and A, D are heavier than B and E. So C is the heaviest, and both statements are needed (c).
4. A different reading of Statement-1 makes the data unclear, which is why (d) is also accepted.
The words 'none of them' can be read two ways, so UPSC's final key accepts both (c) and (d).
Answer as per the official UPSC answer key.
Read the passage
Medieval merchants risked the hazards of the Silk Road to reach the markets of China; Portuguese caravels in the 15 century sailed beyond the bounds of the known world, searching less for knowledge than for gold and spices. Historically, the driver for opening frontiers has always been the search for resources. Science and curiosity are weaker drivers. The only way to open up space, whether the space of solar system or interstellar space is to create an economic engine and that engine is resource extraction.
Which one of the following statements best sums up the passage given above ?
Answer (c) & explanation
The passage is best summed up as: humans explore new frontiers mainly for economic reasons (c). Step 1: it gives examples: medieval merchants on the Silk Road and Portuguese ships seeking gold and spices. Step 2: it says "the driver for opening frontiers has always been the search for resources", and space too needs an economic engine. That is (c). Step 3: option (a) widens it to any human endeavour, but the passage talks only of frontiers. Option (b) predicts space will govern the economy, which is not said. Option (d), risk-taking, is not the main point.
Tip: watch the scope. An option that stretches "frontiers" to "every human activity" goes beyond the passage.
Answer as per the official UPSC answer key.
A bank employee drives 10 km towards South from her house and turns to her left and drives another 20 km. She again turns left and drives 40 km, then she turns to her right and drives for another 5 km. She again turns to her right and drives another 30 km to reach her bank where she works. What is the shortest distance between her bank and her house ?
Answer (b) & explanation
The shortest distance is 25 km (b). Step 1: trace the path. South 10 km. Facing South, left is East: 20 km. Facing East, left is North: 40 km. Facing North, right is East: 5 km. Facing East, right is South: 30 km. Step 2: north-south: −10 + 40 − 30 = 0. She ends on the same level as her house. East: 20 + 5 = 25 km. Step 3: so the bank is 25 km due East of the house. Options (a), (c) and (d) fail.
Tip: add up all north-south moves and all east-west moves separately. If one adds to zero, the answer is simply the other total.
Answer as per the official UPSC answer key.
What is the value of 'X' in the sequence 2, 7, 22, 67, 202, X, 1822 ?
Answer (c) & explanation
X is 607 (c). Step 1: look at how each term is made from the one before. 2 × 3 + 1 = 7; 7 × 3 + 1 = 22; 22 × 3 + 1 = 67; 67 × 3 + 1 = 202. The rule is × 3, then + 1. Step 2: so X = 202 × 3 + 1 = 607. Step 3: check with the next term: 607 × 3 + 1 = 1822. It matches. Options (a) 603, (b) 605 and (d) 608 fail this check.
Tip: when terms grow about three times each step, try "× 3 ± a small number". Always confirm using the term after the blank.
Answer as per the official UPSC answer key.
A person X from a place A and another person Y from a place B set out at the same time to walk towards each other. The places are separated by a distance of 15 km. X walks with a uniform speed of 1·5 km/hr and Y walks with a uniform speed of 1 km/hr in the first hour, with a uniform speed of 1·25 km/hr in the second hour and with a uniform speed of 1·5 km/hr in the third hour and so on. Which of the following is/are correct ?
- 1. They take 5 hours to meet.
- 2. They meet midway between A and B.
Select the correct answer using the code given below :
Answer (c) & explanation
Both statements are correct (c). Step 1: X walks at a steady 1.5 km/hr. In 5 hours X covers 1.5 × 5 = 7.5 km. Step 2: Y's speed rises by 0.25 each hour: 1, 1.25, 1.5, 1.75, 2. In 5 hours Y covers 1 + 1.25 + 1.5 + 1.75 + 2 = 7.5 km. Step 3: together they cover 7.5 + 7.5 = 15 km, the full distance. So they meet after 5 hours (statement 1). Each has walked 7.5 km, which is exactly midway (statement 2). So options (a), (b) and (d) fail.
Tip: Y's speeds average 1.5 km/hr over those 5 hours, the same as X. Equal average speeds for equal time mean equal distance.
Answer as per the official UPSC answer key.