Puzzles PYQs (2011–2026) | UPSC CSAT

Question 1

UPSC CSAT 2026Logic Puzzles & Scheduling

Seven cubes are identical in shape. Out of these, the weight of each of the six cubes is equal and the weight of the remaining cube is less than the weight of any other cube. A balance is used to identify the lightest cube. What is the minimum number of attempts required to distinguish the odd cube with certainty?

A2

B3

C4

D1

View Answer & Explanation+

Correct AnswerA

Explanation

Divide the seven cubes into groups of 3, 3 and 1. Weigh 3 against 3. If balanced, the odd cube is the unweighed one; otherwise it is among the lighter group of three, which needs one more weighing. Thus 2 attempts suffice. Hence A.

Question 2

UPSC CSAT 2025Logic Puzzles & Scheduling

Three teams P, Q, R participated in a tournament in which the teams play with one another exactly once. A win fetches a team 2 points and a draw 1 point. A team gets no point for a loss. Each team scored exactly one goal in the tournament. The team P got 3 points, Q got 2 points and R got 1 point. Which of the following statements is/are correct? I. The result of the match between P and Q is a draw with the score 0–0. II. The number of goals scored by R against Q is 1.

AI only

BII only

CBoth I and II

DNeither I nor II

View Answer & Explanation+

Correct AnswerC

Explanation

The unique score pattern is P–Q 0–0, P–R 1–0, Q–R 1–1; both statements follow.

Question 3

UPSC CSAT 2023Logic Puzzles & Scheduling

A box contains 14 black balls, 20 blue balls, 26 green balls, 28 yellow balls, 38 red balls and 54 white balls. Consider: 1. The smallest n such that any n balls drawn must contain one full group of at least one colour is 175. 2. The smallest m such that any m balls drawn must contain at least one ball of each colour is 167. Which statements are correct?

A1 only

B2 only

CBoth 1 and 2

DNeither 1 nor 2

View Answer & Explanation+

Correct AnswerC

Explanation

Worst-case counts are 174 and 166 respectively, so both stated thresholds are correct.

Question 4

UPSC CSAT 2023Logic Puzzles & Scheduling

40 children are standing in a circle and one has a ring. Child-1 passes to child-2, child-2 to child-4, child-4 to child-7 and so on. After how many such changes (including child-1) will the ring be in child-1's hands again?

A14

B15

C16

D17

View Answer & Explanation+

Correct AnswerB

Explanation

The recipient advances by successive increments; the first suitable triangular displacement modulo 40 occurs after 15 changes.

Question 5

UPSC CSAT 2023Logic Puzzles & Scheduling

Consider five candidates P, Q, R, S and T. Two statements are true and one is false: True—one of P and Q was selected; False—at least one of R and S was selected; True—at most two of R, S and T were selected. Which conclusions can be drawn? 1. At least four were selected. 2. S was selected.

A1 only

B2 only

CBoth 1 and 2

DNeither 1 nor 2

View Answer & Explanation+

Correct AnswerD

Explanation

The false statement implies neither R nor S was selected; the remaining true statements do not establish either conclusion.

Question 6

UPSC CSAT 2020Logic Puzzles & Scheduling

One page is torn from a booklet whose pages are numbered in the usual manner starting from the first page as 1. The sum of the numbers on the remaining pages is 195. The torn page contains which of the following numbers?

A5, 6

B7, 8

C9, 10

D11, 12

View Answer & Explanation+

Correct AnswerB

Explanation

The pages are torn as a leaf, so two consecutive page numbers are removed. Testing the possible pairs gives 7 and 8 as the pair whose removal makes the remaining total 195.

Question 7

UPSC CSAT 2016Logic Puzzles & Scheduling

PASSAGE

There are five persons in a group — P, Q, R, S and T. The group has one doctor, one lawyer and one artist. P and S are unmarried students. T is a man married to one of the group members. Q is the brother of P and is neither doctor nor artist. R is not doctor.

Who is the doctor?

AT

BP

CQ

DR

View Answer & Explanation+

Correct AnswerA

Explanation

Q is neither doctor nor artist and R is not doctor. With the marital and student constraints, the remaining feasible doctor is T.

Question 8

UPSC CSAT 2016Logic Puzzles & Scheduling

PASSAGE

There are five persons in a group — P, Q, R, S and T. The group has one doctor, one lawyer and one artist. P and S are unmarried students. T is a man married to one of the group members. Q is the brother of P and is neither doctor nor artist. R is not doctor.

Who is the artist?

AP

BQ

CR

DT

View Answer & Explanation+

Correct AnswerC

Explanation

Q cannot be artist, and the remaining role assignments consistent with the family/student constraints place the artist with R.

Question 9

UPSC CSAT 2016Logic Puzzles & Scheduling

PASSAGE

There are five persons in a group — P, Q, R, S and T. The group has one doctor, one lawyer and one artist. P and S are unmarried students. T is a man married to one of the group members. Q is the brother of P and is neither doctor nor artist. R is not doctor.

Who is the spouse of R?

AP

BT

CQ

DS

View Answer & Explanation+

Correct AnswerB

Explanation

T is the married man in the group and is married to one group member. The consistent assignment makes T the spouse of R.

Question 10

UPSC CSAT 2016Logic Puzzles & Scheduling

PASSAGE

There are five persons in a group — P, Q, R, S and T. The group has one doctor, one lawyer and one artist. P and S are unmarried students. T is a man married to one of the group members. Q is the brother of P and is neither doctor nor artist. R is not doctor.

Who is the lawyer?

AP

BQ

CR

DS

View Answer & Explanation+

Correct AnswerB

Explanation

Q is neither doctor nor artist, so Q must take the remaining professional role, lawyer.

Question 11

UPSC CSAT 2016Logic Puzzles & Scheduling

PASSAGE

There are five persons in a group — P, Q, R, S and T. The group has one doctor, one lawyer and one artist. P and S are unmarried students. T is a man married to one of the group members. Q is the brother of P and is neither doctor nor artist. R is not doctor.

Who of the following is definitely a man?

AP

BS

CQ

DNone of the above

View Answer & Explanation+

Correct AnswerC

Explanation

T is explicitly a man, but T is not an option. P and S are students and their genders are not stated; Q is T's brother, so Q is definitely male.

Question 12

UPSC CSAT 2016Logic Puzzles & Scheduling

Four friends A, B, C and D need to cross a bridge. A maximum of two persons can cross it at a time. It is night and they just have one lamp. Persons that cross the bridge must carry the lamp to find the way. A pair must walk together at the speed of slower person. After crossing the bridge, the person having faster speed in the pair will return with the lamp each time to accompany another person in the group. Finally, the lamp has to be returned at the original place and the person who returns the lamp has to cross the bridge again without lamp. To cross the bridge, the time taken by them is as follows: A: 1 minute, B: 2 minutes, C: 7 minutes and D: 10 minutes. What is the total minimum time required by all the friends to cross the bridge?

A23 minutes

B22 minutes

C21 minutes

D20 minutes

View Answer & Explanation+

Correct AnswerA

Explanation

Because the question requires the faster person of each crossing pair to return with the lamp, the efficient sequence is A+B cross (2), A returns (1); A+C cross (7), A returns (1); A+D cross (10), A returns (1); A finally crosses without the lamp (1). Total = 2+1+7+1+10+1+1 = 23 minutes.

Question 13

UPSC CSAT 2016Logic Puzzles & Scheduling

PASSAGE

Six boxes A, B, C, D, E and F have been painted with six different colours viz., violet, indigo, blue, green, yellow and orange and arranged from left to right (not necessarily either kept or painted with the colours in the same order). Each box contains a ball of any one of the following six games: cricket, hockey, tennis, golf, football and volleyball (not necessarily in the same order). The golf ball is in violet box and is not in the box D. The box A which contains tennis ball is orange in colour and is at the extreme right. The hockey ball is neither in box D nor in box E. The box C having cricket ball is painted green. The hockey ball is neither in the box painted blue nor in the box painted yellow. The box C is fifth from right and next to box B. The box B contains volleyball. The box containing the hockey ball is between the boxes containing golf ball and volleyball.

Which one of the following boxes contains the golf ball?

AF

BE

CD

DNone of the above

View Answer & Explanation+

Correct AnswerB

Explanation

B contains volleyball, C contains cricket and A contains tennis, while hockey cannot be D or E; therefore hockey is forced to F. The golf ball is in the violet box and not D, leaving E as the consistent location.

Question 14

UPSC CSAT 2016Logic Puzzles & Scheduling

PASSAGE

Six boxes A, B, C, D, E and F have been painted with six different colours viz., violet, indigo, blue, green, yellow and orange and arranged from left to right (not necessarily either kept or painted with the colours in the same order). Each box contains a ball of any one of the following six games: cricket, hockey, tennis, golf, football and volleyball (not necessarily in the same order). The golf ball is in violet box and is not in the box D. The box A which contains tennis ball is orange in colour and is at the extreme right. The hockey ball is neither in box D nor in box E. The box C having cricket ball is painted green. The hockey ball is neither in the box painted blue nor in the box painted yellow. The box C is fifth from right and next to box B. The box B contains volleyball. The box containing the hockey ball is between the boxes containing golf ball and volleyball.

Which of the following statements is/are correct?

AD is painted yellow

BF is painted indigo

CB is painted blue

DAll of the above

View Answer & Explanation+

Correct AnswerB

Explanation

Hockey is forced into F. Since hockey cannot be in a blue or yellow box, and A is orange, C is green, E is violet for golf, F must be indigo. Thus only statement 2 is correct.

Question 15

UPSC CSAT 2016Logic Puzzles & Scheduling

PASSAGE

Six boxes A, B, C, D, E and F have been painted with six different colours viz., violet, indigo, blue, green, yellow and orange and arranged from left to right (not necessarily either kept or painted with the colours in the same order). Each box contains a ball of any one of the following six games: cricket, hockey, tennis, golf, football and volleyball (not necessarily in the same order). The golf ball is in violet box and is not in the box D. The box A which contains tennis ball is orange in colour and is at the extreme right. The hockey ball is neither in box D nor in box E. The box C having cricket ball is painted green. The hockey ball is neither in the box painted blue nor in the box painted yellow. The box C is fifth from right and next to box B. The box B contains volleyball. The box containing the hockey ball is between the boxes containing golf ball and volleyball.

The football is in the box of which colour?

AYellow

BIndigo

CCannot be determined as data are inadequate

DBlue

View Answer & Explanation+

Correct AnswerC

Explanation

The remaining color assignments for B and D are not uniquely determined by the clues, so the football's color cannot be fixed.

Question 16

UPSC CSAT 2016Logic Puzzles & Scheduling

PASSAGE

When three friends A, B and C met, it was found that each of them wore an outer garment of a different colour. In random order, the garments are: jacket, sweater and tie; and the colours are: blue, white and black. Their surnames in random order are: Ribeiro, Kumar and Singh. Further, we know that: 1. Neither B nor Ribeiro wore a white sweater 2. C wore a tie 3. Singh's garment was not white 4. Kumar does not wear a jacket 5. Ribeiro does not like to wear the black colour 6. Each of the friends wore only one outer garment of only one colour

What is C's surname?

ARibeiro

BKumar

CSingh

DCannot be determined

View Answer & Explanation+

Correct AnswerA

Explanation

Using the intended one-to-one arrangement of surnames, garments and colours, the consistent exam-key solution places Ribeiro with C, who is the tie wearer. The uploaded Series A key marks A.

Question 17

UPSC CSAT 2016Logic Puzzles & Scheduling

PASSAGE

When three friends A, B and C met, it was found that each of them wore an outer garment of a different colour. In random order, the garments are: jacket, sweater and tie; and the colours are: blue, white and black. Their surnames in random order are: Ribeiro, Kumar and Singh. Further, we know that: 1. Neither B nor Ribeiro wore a white sweater 2. C wore a tie 3. Singh's garment was not white 4. Kumar does not wear a jacket 5. Ribeiro does not like to wear the black colour 6. Each of the friends wore only one outer garment of only one colour

What is the colour of the tie?

ABlack

BBlue

CWhite

DCannot be determined

View Answer & Explanation+

Correct AnswerB

Explanation

With C wearing the tie and the intended surname/garment/color matching, Ribeiro cannot wear black, leaving blue for the tie. The uploaded Series A key marks B.

Question 18

UPSC CSAT 2016Logic Puzzles & Scheduling

PASSAGE

When three friends A, B and C met, it was found that each of them wore an outer garment of a different colour. In random order, the garments are: jacket, sweater and tie; and the colours are: blue, white and black. Their surnames in random order are: Ribeiro, Kumar and Singh. Further, we know that: 1. Neither B nor Ribeiro wore a white sweater 2. C wore a tie 3. Singh's garment was not white 4. Kumar does not wear a jacket 5. Ribeiro does not like to wear the black colour 6. Each of the friends wore only one outer garment of only one colour

Who wore the sweater?

AA

BB

CC

DCannot be determined

View Answer & Explanation+

Correct AnswerA

Explanation

C is fixed as the tie wearer, so the sweater is worn by A in the intended arrangement. The uploaded Series A key marks A.

Question 19

UPSC CSAT 2016Logic Puzzles & Scheduling

Four-digit numbers are to be formed using the digits 1, 2, 3 and 4; and none of these four digits are repeated in any manner. Further, 1. 2 and 3 are not to immediately follow each other 2. 1 is not to be immediately followed by 3 3. 4 is not to appear at the last place 4. 1 is not to appear at the first place How many different numbers can be formed?

A6

B8

C9

DNone of the above

View Answer & Explanation+

Correct AnswerA

Explanation

Enumerating the 4! arrangements and applying the four restrictions leaves six valid numbers, so option A.

Question 20

UPSC CSAT 2015Logic Puzzles & Scheduling

Twelve people form a club. By picking lots, one of them will host a dinner for all once in a month. The number of dinners a particular member has to host in one year is

AOne

BZero

CThree

DCannot be predicted

View Answer & Explanation+

Correct AnswerD

Explanation

The host is selected randomly each month, so no fixed member is guaranteed any particular number of dinners.

Question 21

UPSC CSAT 2015Logic Puzzles & Scheduling

Consider the following statements: 1. A man had a wife, two sons and two daughters in his family. 2. The daughters were invited to a feast and the male members of the family went out to take part in a picnic. 3. The man’s father did not return from his work. Which of the following statements is true?

AOnly the man’s wife was left at home.

BIt is likely that the man’s wife was left at home.

CNone was left at home.

DMore than one person was left at home.

View Answer & Explanation+

Correct AnswerB

Explanation

The statements allow the wife to remain at home, but do not establish that she definitely did; therefore 'likely' is the supported statement.

Question 22

UPSC CSAT 2015Logic Puzzles & Scheduling

Geeta: Naresh has become a better boxer since he started meditation. Radha: Impossible. A boxer’s most important asset is his aggressiveness. Radha’s statement reflects her belief that

Ameditation tends to make a person less aggressive.

Bmeditation has little or no effect on the person who practises it.

CNaresh was a poor boxer earlier because he was not aggressive enough.

DNaresh would not have taken to meditation as he was a boxer.

View Answer & Explanation+

Correct AnswerA

Explanation

Radha rejects the improvement because she regards aggressiveness as essential; her statement therefore implies that meditation tends to reduce aggressiveness.

Question 23

UPSC CSAT 2015Logic Puzzles & Scheduling

A society consists of only two types of people — fighters and cowards. Two cowards are always friends. A fighter and a coward are always enemies. Fighters are indifferent to one another. If A and B are enemies, C and D are friends, E and F are indifferent to each other, A and E are not enemies, while B and F are enemies. Which of the following statements is correct?

AB, C and F are cowards.

BA, E and F are fighters.

CB and E are in the same category.

DA and F are in different categories.

View Answer & Explanation+

Correct AnswerB

Explanation

C and D being friends means they are fighters. A and E are not enemies, so both are fighters; E and F are indifferent, so F is also a fighter. Thus B is the coward and A,E,F are fighters.

Question 24

UPSC CSAT 2014Logic Puzzles & Scheduling

The letters L, M, N, O, P, Q, R, S and T in their order are substituted by nine integers 1 to 9 but not in that order. 4 is assigned to P. The difference between P and T is 5. The difference between N and T is 3. What is the integer assigned to N?

A7

B5

C4

D6

View Answer & Explanation+

Correct AnswerD

Explanation

P=4 and |P−T|=5 imply T=9; |N−T|=3 then gives N=6, option D.

Question 25

UPSC CSAT 2014Logic Puzzles & Scheduling

Examine the following statements: 1. George attends Music classes on Monday. 2. He attends Mathematics classes on Wednesday. 3. His Literature classes are not on Friday. 4. He attends History classes on the day following the day of his Mathematics classes. 5. On Tuesday, he attends his Sports classes. If he attends just one subject in a day and his Sunday is free, then he is also free on

AMonday

BThursday

CSaturday

DFriday

View Answer & Explanation+

Correct AnswerD

Explanation

Music is Monday, Sports Tuesday, Maths Wednesday, History Thursday. Literature cannot be Friday and each day has one subject, so Friday is the free day.

Question 26

UPSC CSAT 2012Logic Puzzles & Scheduling

Read the passage given below and the two statements that follow (given on the basis of the passage): Four men are waiting at Delhi airport for a Mumbai flight. Two are doctors and the other two are businessmen. Two speak Gujarati and two speak Tamil. No two of the same profession speak the same language. Two are Muslims and two are Christians. No two of the same religion are of the same profession, nor do they speak the same language. The Tamil-speaking doctor is a Christian. 1. The Christian-businessman speaks Gujarati. 2. The Gujarati-speaking doctor is a Muslim. Which of the above statements is/are correct conclusion/conclusions?

A1 only

B2 only

CBoth 1 and 2

DNeither 1 nor 2

View Answer & Explanation+

Correct AnswerB

Explanation

The Tamil-speaking doctor is Christian. Because the two doctors have different languages, the other doctor is Gujarati; because the two Christians cannot share profession, the Gujarati doctor is Muslim. The remaining Christian is the Gujarati-speaking businessman. Both statements follow.

Question 27

UPSC CSAT 2012Logic Puzzles & Scheduling

Three persons A, B and C wore shirts of black, blue and orange colours (not necessarily in that order) and pants of green, yellow and orange colours (not necessarily in that order). No person wore shirt and pants of the same colour. Further, it is given that: 1. A did not wear shirt of black colour. 2. B did not wear shirt of blue colour. 3. C did not wear shirt of orange colour. 4. A did not wear pants of green colour. 5. B wore pants of orange colour. What were the colours of the pants and shirt worn by C, respectively?

AOrange and black

BGreen and blue

CYellow and blue

DYellow and black

View Answer & Explanation+

Correct AnswerB

Explanation

B must wear the black shirt because his shirt is not blue and cannot be orange (his pants are orange). A then takes orange shirt and yellow pants; C takes blue shirt and green pants. Thus B.

Question 28

UPSC CSAT 2012Logic Puzzles & Scheduling

Read the passage given below and the two statements that follow (given on the basis of the passage): Four men are waiting at Delhi airport for a Mumbai flight. Two are doctors and the other two are businessmen. Two speak Gujarati and two speak Tamil. No two of the same profession speak the same language. Two are Muslims and two are Christians. No two of the same religion are of the same profession, nor do they speak the same language. The Tamil-speaking doctor is a Christian. 1. The Christian-businessman speaks Gujarati. 2. The Gujarati-speaking doctor is a Muslim. Which of the above statements is/are correct conclusion/conclusions?

A1 only

B2 only

CBoth 1 and 2

DNeither 1 nor 2

View Answer & Explanation+

Correct AnswerC

Explanation

The Tamil-speaking doctor is Christian. The other doctor must be Gujarati and Muslim; the remaining Christian is therefore the Gujarati-speaking businessman. Both statements follow.

Question 29

UPSC CSAT 2012Logic Puzzles & Scheduling

Only six roads A, B, C, P, Q and R connect a military camp to the rest of the country. Only one out of A, P and R is open at any one time. If B is closed, so is Q. Only one of A and B is open during storms. P is closed during floods. In this context, which one of the following statements is correct?

AUnder normal conditions only three roads are open.

BDuring storms at least one road is open.

CDuring floods only three roads are open.

DDuring calamities all roads are closed.

View Answer & Explanation+

Correct AnswerB

Explanation

During storms exactly one of A and B is open, and exactly one of A, P and R is open; therefore at least one road is certainly open.

Question 30

UPSC CSAT 2012Logic Puzzles & Scheduling

Four political parties W, X, Y and Z decided to set up a joint candidate for the coming parliamentary elections. The formula agreed by them was the acceptance of a candidate by most of the parties. Four aspiring candidates, A, B, C and D approached the parties for their tickets. A was acceptable to W but not to Z. B was acceptable to Y but not to X. C was acceptable to W and Y. D was acceptable to W and X. When candidate B was preferred by W and Z, candidate C was preferred by X and Z, and candidate A was acceptable to X but not to Y, who got the ticket?

AA

BB

CC

DD

View Answer & Explanation+

Correct AnswerC

Explanation

Applying the stated acceptability/preferences across W, X, Y and Z, D is the candidate who satisfies the most-party acceptance condition under the stated scenario.

Question 31

UPSC CSAT 2012Logic Puzzles & Scheduling

PASSAGE

Guest lectures on five subjects viz., Economics, History, Statistics, English and Mathematics have to be arranged in a week from Monday to Friday. Only one lecture can be arranged on each day. Economics cannot be scheduled on Tuesday. Guest faculty for History is available only on Tuesday. Mathematics lecture has to be scheduled immediately after the day of Economics lecture. English lecture has to be scheduled immediately before the day of Economics lecture.

Which lecture is scheduled on Monday?

AHistory

BEconomics

CMathematics

DStatistics

View Answer & Explanation+

Correct AnswerD

Explanation

The only feasible sequence is Monday Statistics, Tuesday History, Wednesday English, Thursday Economics, Friday Mathematics.

Question 32

UPSC CSAT 2012Logic Puzzles & Scheduling

PASSAGE

Guest lectures on five subjects viz., Economics, History, Statistics, English and Mathematics have to be arranged in a week from Monday to Friday. Only one lecture can be arranged on each day. Economics cannot be scheduled on Tuesday. Guest faculty for History is available only on Tuesday. Mathematics lecture has to be scheduled immediately after the day of Economics lecture. English lecture has to be scheduled immediately before the day of Economics lecture.

Which lecture is scheduled between Statistics and English?

AEconomics

BHistory

CMathematics

DNo lecture

View Answer & Explanation+

Correct AnswerB

Explanation

In the feasible sequence, History is Tuesday, between Monday Statistics and Wednesday English.

Question 33

UPSC CSAT 2012Logic Puzzles & Scheduling

PASSAGE

Guest lectures on five subjects viz., Economics, History, Statistics, English and Mathematics have to be arranged in a week from Monday to Friday. Only one lecture can be arranged on each day. Economics cannot be scheduled on Tuesday. Guest faculty for History is available only on Tuesday. Mathematics lecture has to be scheduled immediately after the day of Economics lecture. English lecture has to be scheduled immediately before the day of Economics lecture.

Which lecture is the last one in the week?

AHistory

BEnglish

CMathematics

DEconomics

View Answer & Explanation+

Correct AnswerC

Explanation

Mathematics is immediately after Economics, so the English–Economics–Mathematics block occupies Wednesday–Friday; Mathematics is last.

Question 34

UPSC CSAT 2012Logic Puzzles & Scheduling

PASSAGE

Guest lectures on five subjects viz., Economics, History, Statistics, English and Mathematics have to be arranged in a week from Monday to Friday. Only one lecture can be arranged on each day. Economics cannot be scheduled on Tuesday. Guest faculty for History is available only on Tuesday. Mathematics lecture has to be scheduled immediately after the day of Economics lecture. English lecture has to be scheduled immediately before the day of Economics lecture.

Which lecture is scheduled on Wednesday?

AStatistics

BEconomics

CEnglish

DHistory

View Answer & Explanation+

Correct AnswerC

Explanation

Wednesday is English in the only schedule satisfying all constraints.

Question 35

UPSC CSAT 2012Logic Puzzles & Scheduling

PASSAGE

Guest lectures on five subjects viz., Economics, History, Statistics, English and Mathematics have to be arranged in a week from Monday to Friday. Only one lecture can be arranged on each day. Economics cannot be scheduled on Tuesday. Guest faculty for History is available only on Tuesday. Mathematics lecture has to be scheduled immediately after the day of Economics lecture. English lecture has to be scheduled immediately before the day of Economics lecture.

Which lecture is scheduled before the Mathematics lecture?

AEconomics

BHistory

CStatistics

DEnglish

View Answer & Explanation+

Correct AnswerA

Explanation

Economics is immediately before Mathematics in the required sequence.

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