32 Logical Deduction Puzzles with Answers: From Easy to Challenging

Looking to test your brainpower or challenge your friends to a battle of wits? Look no further, as we’ve put together the ultimate list of brainteasers and logical deduction puzzles to challenge even the most practiced of riddle-solvers. You’ll find classic logic puzzle themes like “truth or lie” and “crossing the river,” as well as funny, dark, easy, and impossibly-hard riddles. Get puzzlin’!

Section 1 of 8:

Easy Logic Riddles & Solutions

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1
There are two ducks in front of a duck, two ducks behind a duck and a duck in the middle. How many ducks are there?^{[1]
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- Answer: Three.
- Explanation: Two ducks are in front of the last duck. The first duck has two ducks behind them, and there’s one duck between the other two.
2
Five people were eating apples, A finished before B, but behind C. D finished before E, but behind B. What was the finishing order?^{[2]
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- Answer: CABDE.
- Explanation: If you start with the first three people, A finished before B but after C, giving us the order CAB. Then, we know that D finished before B, creating CABD. Finally, we know E finished after D; CABDE.
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3
Robert is looking at Emma. Emma is looking at Guy. Robert is married, Guy is not, and we don't know if Emma is married. Is a married person looking at an unmarried person?^{[3]
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- Answer: Yes.
- Explanation: If Emma is married, she’s married and looking at Guy, who’s unmarried. If Emma is unmarried, then Robert (who is married) is looking at her. In either case, there is a married person looking at an unmarried one.
4
The day before two days after the day before tomorrow is Saturday. What day is it today?^{[4]
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- Answer: Today is Friday.
- Explanation: The “day before tomorrow” is today, and the “day before two days after” is really just one day after. So, simplified, the statement would read “one day after today is Saturday.” One day after Saturday is Friday, which gives us our answer.
5
I am your mother's brother's only brother in law. Who am I?
- Answer: Your father.
- Explanation: Your mother’s brother is your uncle. Your uncle’s brother-in-law is your mother’s husband, or your father.

Section 2 of 8:

Hard Logic Riddles & Solutions

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1
There is a barrel with no lid and some wine in it. "This barrel of wine is more than half full," says the woman. "No, it's not," says the man. "It's less than half full." Without any measuring implements and without removing any wine from the barrel, how can they easily determine who is correct?
- Answer & Explanation: Tilt the barrel until the wine just touches the barrel’s lip. If they can see the bottom of the barrel, then it’s less than half full. If they can’t see the bottom of the barrel because it’s still covered by wine, then it’s more than half full.
2
Three men are lined up behind each other. The tallest man is in the back and can see the heads of the two in front of him; the middle man can see the one man in front of him; the man in front can't see anyone. They are blindfolded, and hats are placed on their heads, picked from three black hats and two white hats. The extra two hats are hidden, and the blindfolds are removed. The tallest man is asked if he knows what color hat he's wearing; he doesn't. The middle man is asked if he knows; he doesn't. But the man in front, who can't see anyone, says he knows. How does he know, and what color hat is he wearing?^{[5]
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- Answer: Black.
- Explanation: The man in the front knew that he and the middle man aren’t both wearing white hats. Otherwise, the man in the back would’ve known that he had a black hat (since there are only two white hats). The man in the front also knows that the middle man didn’t see with a white hat because, if he did, the middle man would’ve known that he himself was wearing a black hat. As a result, the front man knows that his hat must be black.
3
There are three crates, one with mangos, one with coconuts and one with both mangos and coconuts mixed. Each crate is closed and labeled with one of three labels: “Mangos,” “Coconuts,” or “Mangos and Coconuts.” The label maker broke and labeled all of the crates incorrectly. How could you pick just one fruit from one crate to figure out what's in each crate?^{[6]
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- Answer: Pick a fruit from the crate marked “Mangos and Coconuts.”
- Explanation: If you pick a mango, then you know that that crate should be labeled as “Mangos” because all of the crates are marked incorrectly as of now. So, the crate marked “Mangos” must be “Coconuts”—if it were labeled as “Mangos and Coconuts,” then the “Coconuts” crate would be labeled correctly, which we know isn’t the case. The one marked “Coconuts” is “Mangos and Coconuts.” On the other hand, if you pick a coconut from the crate, then you know that the crate should be marked “Coconuts”, the one marked “Coconuts” must be “Mangos,” and the one marked “Mangos” must be “Mangos and Coconuts.”
4
A teacher writes six words on a board: "cat dog has max dim tag." She gives three students, Aurora, Belle, and Cindy, each a piece of paper with one letter from one of the words and explains that together, their letters spell one of the words. She asks, "Aurora, do you know the word?" Aurora immediately replies yes. She asks, "Belle, do you know the word?" Belle thinks for a moment and replies, "Yes." Then, the teacher asks Cindy the same question. She thinks and then replies, "Yes." What is the word?^{[7]
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- Answer: “Dog.”
- Explanation: Aurora knows because she has one of the unique letters that only appears once in all the words: c, o, h, s, x, i. (In this case, it’s “o.”) None of these letters appear in “tag,” so that word is eliminated. All of these unique letters appear in different words, except for the “h” and “s” in “has.” Using this logic, Belle can then figure out what the word is based on the leftover unique letters: t, g, h, s. This eliminates “max” and “dim.” Thus, Belle has “g.” Cindy can then figure out the word because there’s only one unique letter left (“d”), so the word must be “dog.”
5
You are given three doors to choose from, one of which contains a car, and the other two contain goats. After you've chosen one but haven't opened it, Monty, who knows where everything is, reveals the location of a goat from behind one of the other two doors. Should you stick with your original choice or switch if you want the car?^{[8]
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- Answer: Switch.
- Explanation: At the beginning, you have a 1 in 3 chance of picking the car—the two doors with the goats have ⅔ of the chance. However, because Monty knows and shows you where one of the goats is, the ⅔ chance is placed solely on the third door. So, the odds are better if you switch.
6
Clementine put Maude in a room with three light switches. Maude had to figure out which light was controlled by each switch. All of the lights, however, were in the room next door. The switches in the room were all off, and Maude was only allowed to turn them on or off when the door was closed. The door blocked all of the light coming in from the other room. Once she opened the door, she was no longer able to turn on or off any of the light switches. Assuming that all the lights were working, how did Maude figure it out?^{[9]
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- Answer & Explanation: Mauve should turn on the first two light switches and water for a few minutes. Then, she should turn off the second switch and open the door to go into the room. Looking at the two lights that are off, she feels each bulb to see which one is warm or hot. She’ll know which switch controls each light by observing: which light is on (controlled by the first switch); which light is warm to the touch (controlled by the second switch); and which light is cold or not warm (controlled by the third switch).

Section 3 of 8:

Dark Logic Riddles & Solutions

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1
An assassin is playing Russian roulette with a six-shooter revolver. He puts in one bullet, spins the chambers, and fires at you, but no bullet comes out. He gives you the choice of whether or not he should spin the chambers again before firing a second time. Should he spin again?^{[10]
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- Answer: Yes.
- Explanation: Before he spins, there’s a 1 in 6 chance of a bullet being fired. Once he spins, however, one of those chances is taken away, creating a 1 in 5 chance that a bullet will be fired. So, it’s better to spin again for a reduced chance of a bullet being fired.
2
An assassin is playing Russian roulette with a six-shooter revolver. He puts TWO bullets in consecutive chambers, spins the chambers, and fires at you, but no bullet comes out. He gives you the choice of whether or not he should spin the chambers again before firing a second time. Should you tell him to spin the chambers again?
- Answer: No.
- Explanation: When you have 2 bullets, you have a 2 in 6 (or 1 in 3) chance to get hit with a bullet before the assassin fires the first time. We know that the empty shot in the previous round was one of four empty chambers, leaving four positions that the gun could now be in, only one of which would emit a bullet. Therefore, you have a 1 in 4 chance that the second round will fire. 1 in 4 is better odds than 1 in 3, so you should tell him not to shoot again.
3
A man is caught on the king's property. He is brought before the king to be punished. The king says, "You must give me a statement. If it is true, you will be killed by lions. If it is false, you will be killed by the trampling of wild buffalo. If I can't figure it out, I'll have to let you go." Sure enough, the man was released. What was the man's statement?^{[11]
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- Answer: “I will be killed by the trampling of wild buffalo.”
- Explanation: If this statement is true, the man will be killed by lions, which would make the statement not true. If it’s a lie, he’d be killed by wild buffalo, making the statement true. The king couldn’t figure out a solution, so he had to let the man live.
4
A murderer is condemned to death. He has to choose between three rooms. The first is full of raging fires, the second is full of assassins with loaded guns, and the third is full of lions that haven't eaten in 3 years. Which room is safest for him?^{[12]
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- Answer: The third room.
- Explanation: Those lions haven’t eaten in three years, so they’re dead!

Section 4 of 8:

Funny Logic Riddles & Solutions

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1
How many bricks does it take to complete a building made of brick?
- Answer: 1.
- Explanation: It only takes one brick (the last one) to complete a building.
2
There are only two barbers in town. One of them has a nice, neatly trimmed head of hair. The other one's hair is a complete mess. Which of the two barbers should you go to and why?^{[13]
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- Answer: Go to the one with the messy hair.
- Explanation: It’s safe to assume that these barber’s cut one another’s hair, meaning that the barber with the messy cut must have cut the neat trim on the other barber’s head. This means that he’s more skilled and a better choice for your cut.
3
Ruby and Lewis are expecting triplets. They already know what they will name their three children, but they aren’t sharing the names until the babies are born. For now, this is all they’ll say: “All three babies are boys.” Their names are also six letters long and anagrams of one another. Their names include both of their parents’ initials, but none of the other letters in their parents’ first names. What will Ruby and Lewis name their triplets?^{[14]
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- Answer: Arnold, Roland, and Ronald.
- Explanation: These three names are all boy names. Each one is six letters long and is an anagram of the other two names. All three names include “R” and “L,” the parents’ initials, but the other letters in their parents’ names (U, B, Y, E, W, I, S) are not present.

Section 5 of 8:

Mathematical Logic Riddles & Solutions

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1
A man has 53 socks in his drawer: 21 identical blue, 15 identical black and 17 identical red. The lights are out, and he is completely in the dark. How many socks must he take out to make 100 percent certain he has at least one pair of black socks?^{[15]
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- Answer: He must take out 40 socks.
- Explanation: If he removes 38 socks (the sum of the two biggest groups: 21 and 17), then it’s possible that they’re all light blue and red (not black). To make sure that he also has a pair of black socks, he must take out two more socks, making 40 total.
2
You have two ropes that each take an hour to burn; however, they burn at inconsistent rates. How can you measure 45 minutes? (You can light one or both ropes at one or both ends at the same time.)^{[16]
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- Answer & Explanation: Both ropes burn inconsistently, so you can’t light one and wait until it’s 75% burned. Instead, you should simultaneously light the first rope at both ends and the second one at one end. The first rope will take 30 minutes to burn, since it’s burning at the same pace from both ends. Once the first rope goes out, light the other end of the second rope. Since the second rope has already been burning for 30 minutes, the remaining rope will take another 30. Lighting it from both ends will halve that time to 15 minutes, giving you 45 minutes total.
3
Sigrid and Lenny decided to play tennis against each other. They bet $1 on each game they played. Sigrid won three bets and Lenny won $5. How many games did they play?
- Answer: Eleven.
- Explanation: Lenny lost 3 games to Sigrid, so he lost $3 (or $1 per game). To win back that $3, Lenny had to win three more games, then win an additional five games to win $5.
4
If five cats can catch five mice in five minutes, how long will it take one cat to catch one mouse?^{[17]
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- Answer: Five minutes.
- Explanation: It would take one cat 25 minutes to catch all five mice, because 5 multiplied by 5 is 25. If we work backward and divide 25 by 5, you’ll get five minutes for one cat to catch each mouse.
5
There are three bags, each containing two marbles. Bag A contains two white marbles, Bag B contains two black marbles and Bag C contains one white marble and one black marble. You pick a random bag and take out one marble, which is white. What is the probability that the remaining marble from the same bag is also white?^{[18]
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- Answer: 2 out of 3.
- Explanation: We know that we don’t have Bag B. Bag A has two white marbles, so we could pick either marble in the bag. If you consider the marbles from Bag A and Bag C as a total count of four marbles (3 white and 1 black), you’ll have a better chance of picking another white marble.

Section 6 of 8:

“Lies or Truth” Logic Riddles & Solutions

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1
If I say "everything I tell you is a lie," am I telling you the truth or a lie?
- Answer: It’s a lie.
- Explanation: It’s impossible for “everything I tell you is a lie” to be the truth because the person is admitting that all of their words are lies. So, this statement itself must be a lie.
2
You're at a fork in the road in which one direction leads to the City of Lies (where everyone always lies) and the other to the City of Truth (where everyone always tells the truth). There's a person at the fork who lives in one of the cities, but you're not sure which one. What question could you ask the person to find out which road leads to the City of Truth?^{[19]
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- Answer: “Which direction do you live in?”
- Explanation: If you ask this question and the person is from the City of Lies, then they will lie and point to the City of Truth. If they’re from the City of Truth, they’ll tell the truth and also point to the City of Truth. Either way, you get your answer!
3
In the forest, a girl encounters a lion and a unicorn. Every Monday, Tuesday, and Wednesday, the lion tells lies, but on the other days, he tells the truth. The unicorn tells the truth the rest of the week but lies on Thursdays, Fridays, and Saturdays. The lion confessed to the girl, “Yesterday I was lying.” So was I, the unicorn said. When is it today?^{[20]
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- Answer: Thursday.
- Explanation: The lion is telling the truth today so must have been lying yesterday. That means that today must be Thursday. Similarly, the unicorn was lying on Thursday and spoke the truth Tuesday. So, when he says that he lied yesterday, that’s a lie (because he lies on Thursdays).
4
There are three people (Astrid, Beatriz, and Cordelia). One of them is a knight, one’s a knave, and one’s a spy. The knight always tells the truth, the knave always lies, and the spy can either lie or tell the truth. Astrid says that Cordelia is a knave. Beatriz says that Astrid is a knight. Cordelia says that she is the spy. Who is the knight, who’s the knave, and who’s the spy?^{[21]
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- Answer: Astrid is the knight, Beatriz is the spy, and Cordelia is the knave.
- Explanation: We know that Beatriz must be lying because, if she was telling the truth, we’d have two knights. So, that means that Beatriz must be either the knave or the spy. Cordelia also cannot be the knight because her statement would then be a lie. By process of elimination, we then know that Astrid is the knight, meaning Beatriz is the spy (because the spy sometimes tells the truth), and Cordelia is the knave.
5
You meet three gods on a mountaintop. One always tells the truth, one always lies and one tells the truth or lies randomly. They understand English but answer in their own language, with ja or da for yes and no. We’ll call them Truth, False, and Random—but you don't know which is which. You can ask three questions to any of the gods (and you can ask the same god more than one question), and they will answer with ja or da. What three questions do you ask to figure out who's who?^{[22]
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- Warning: This problem is often called the hardest logic puzzle ever.
- Answer & Explanation: Start by thinking of a hypothetical question that you know the answer to, like “Does two plus two equal four?” Then, phrase the question like an embedded question—“If I asked you if 2 plus 2 equals 4, would you answer ja?” If ja means “yes,” then Truth would answer ja, but so would False. If ja means “no,” then both would still answer ja. Random’s answer would be meaningless because we don’t know whether he lies or tells the truth.
  
  Then, consider if you said something like, "If I asked you if two plus two equals five, would you answer ja?" If ja means “yes,” Truth and False would both answer da. If ja means “no,” then they’d also both answer “da.” So, you know that, if the embedded question is correct, then Truth and False would always answer with whatever word you used. If the embedded question is incorrect, they’ll always answer with the opposite word of what you said.
  
  Now that you’ve determined the logic of these questions, ask the middle god your first question: "If I asked you whether the god on my left is Random, would you answer ja?" If the god answers ja and you’re talking to either Truth or False, you know that the embedded question is correct and that the god to the left is Random. It’s possible that you just asked Random the question, but you still know that the god on the right is not Ransom. If the answer is da, then you know that the god on the left is not random.
  
  Now, ask the god that you definitely know isn’t Random a question with the same structure, e.g., "If I were to ask you if you are Truth, would you say ja?" If they answer ja, you know you’re talking to Truth. If they answer with da, you know you’re talking to False. Once you’ve identified a god as True or False, ask the same god a final question: "If I asked you if the god in the middle is Random, would you say ja?” From the answer to this question, you can use the process of elimination to identify Random.

Section 7 of 8:

“Crossing a River” Logic Riddles & Solutions

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1
A farmer wants to cross a river and take with him a wolf, a goat and a cabbage. He has a boat, but it can only fit himself, plus either the wolf, the goat or the cabbage. If the wolf and the goat are alone on one shore, the wolf will eat the goat. If the goat and the cabbage are alone on the shore, the goat will eat the cabbage. How can the farmer bring the wolf, the goat, and the cabbage across the river without eating anything?^{[23]
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- Answer & Explanation: The farmer must first take the goat across the river. Then, he returns alone and takes the wolf across but returns with the goat. The farmer then leaves the goat, takes the cabbage, and leaves the cabbage with the wolf before returning alone to get the goat.
2
Four people (Amelia, Björn, Chelsea, and Dusty) want to cross a river in a boat that can only carry 100 kg (220 lb). Amelia weighs 90 kg (200 lb), Björn weighs 80 kg (180 lb), Chelsea weighs 60 kg (130 lb) and Dusty weighs 40 kg (88 lb), and they have 20 kg (44 lb) of supplies. How do they get across?^{[24]
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- Answer & Explanation: Chelsea and Dusty row across first, with a combined weight of 100 kg (220 lb). Dusty returns. Amelia then rows over, and Chelsea returns. Chelsea and Dusty row across again, and Dusty returns. Björn rows across with the supplies (a combined weight of 100 kg (220 lb)). Chelsea then returns before rowing across again with Dusty.
- This puzzle has a couple of possible variations to the solution, but this is the most common one.
3
Four people are crossing a bridge at night, so they all need a torch—but they just have one that only lasts 15 minutes. Angie can cross in one minute, Benny in two minutes, Charley in five minutes and Darlissa in eight minutes. No more than two people can cross at a time; and when two cross, they have to go at the slower person's pace. How do they get across in 15 minutes?^{[25]
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- Answer & Explanation: Angie and Benny cross first in two minutes. Angie returns alone with the torch in one minute. The two slowest people (Charley and Darlissa) cross in eight minutes. Benny returns in two minutes, then Angie and Benny cross in two minutes. 2 + 1 + 8 + 2 + 2 = 15
4
A traveling salesman was trying to cross a river with a cat, a mouse, and a bag of delicious candy. He saw a small boat on the river, but it was so small that he could only take one of his items with him at a time across the river. If he leaves the cat alone with the mouse, the cat will definitely catch and eat it. If he leaves the mouse alone with the candy, the mouse will get into the bag and eat it. How does he get everything across the river safely?^{[26]
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- Answer & Explanation: The salesman must first take the mouse and place him on the other side. Then, the salesman picks up the candy and takes it over the river, but returns with the mouse. The salesman leaves the mouse, grabs the cat, and takes it across the river. He then returns alone, picks up the mouse, and brings it to the other side.