15 tricky riddles to train lateral thinking

2024 Author: Malcolm Clapton | [email protected]. Last modified: 2023-12-17 03:44

A selection of author's problems from the book "Lateral Logic" by Gareth Moore to warm up the brain. Check if you can handle them.

– 1 –

A man walks into a bar and asks for a glass of water. Instead, the bartender suddenly slams the tray onto the counter and yells at the customer in the face. Why?

The man asked for a glass of water because he has hiccups. The bartender realized this and tried to rid the visitor of the hiccups by scaring him. To do this, he first provoked a sharp loud sound, banging the tray on the counter, and then yelled at the man.

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– 2 –

The farmer has a big dog, a small dog, a cat, a chicken and some grain. If you leave them unattended, the dog will attack the dog, the dog will attack the cat, the cat will attack the chicken, and the chicken will eat the grain. The farmer, with all his possessions, needs to get across the river, but the boat is too small for the farmer to carry more than two at a time. How to act so that no one and nothing is eaten and no one is attacked?

Move the dog and the chicken, come back unloaded and carry the dog and the grain. Come back with the dog or chicken, and then move the cat. Come back unloaded and move the dog and chicken.

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– 3 –

You have to deliver an order for a dinner party, but due to planning flaws, you are in a situation where the wine you need is not in the delivery plan. The hostess who made the order is very concerned that the wine is exactly in the quantity indicated by her - exactly 6 liters. And all you have are three containers, which, as you know, can contain exactly 2, 5 and 7 liters, respectively.

The 2L and 5L containers are empty and the 7L container is full. You also have a keg that you can use to transfer liquid from container to container without spilling anything. How to measure exactly 6 liters of wine? You need to find the exact solution - not good by eye!

Pour C into B - into A, B and C, respectively, you get 0, 5 and 2 liters. Pour B into A: 2, 3 and 2 liters. Then A to C: 0, 3 and 4 liters. After that B in A: 2, 1 and 4 l. Finally, A in C: 0, 1 and 6 L. The problem has been resolved.

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– 4 –

I went for a walk and witnessed a crime. The man was tied to the seat of his car and his pockets were cleaned. All the doors and trunk of the car are locked, the windows are completely closed, the car is not damaged. In addition, after committing a crime, the thief did not lock the doors. How is this possible?

This is a convertible that has been opened.

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– 5 –

You have three instances of the hourglass. Each watch can only be used once. Once you turn them over, the reverse movement of the sand is impossible due to the special valve in the center.

Each of the three watches is designed for a different time of pouring sand.

• The first hourglass is poured in 1 minute.
• The second - in 4 minutes.
• Still others - in 7 minutes.

You need to measure a certain time - 10 minutes. How can I do this to the nearest minute using only three available hourglass instances?

Flip all clocks at the same time - 1, 4 and 7 minutes. When, in the clock, the sand is poured to the end for 1 minute, turn the clock by 4 minutes: this clock will have a pause, since the sand cannot be poured in the opposite direction, which means that sand will remain in them for 3 minutes.

When the sand is completely poured in the clock for 7 minutes, turn the clock over for 4 minutes again and let the sand remaining in it fill up to the end: it will pour for another 3 minutes. The total time is 10 minutes.

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– 6 –

Rodrik recently moved to a quiet village in the outback and is just starting to get to know the locals. After living in a new place for a month, he decides to have a haircut. There are two hairdressers in the village, their salons are on the main street, but at different ends of it, so Rodrik needs to decide who to choose.

The hairdresser, whose salon is located at the entrance to the village, always sports a great hairstyle, his hair is cut evenly and well styled. In contrast, the hairdresser from the salon at the far end of the street, near the local park, has unkempt hair and no style. Which hairdresser should Rodrik choose?

Rodrik needs to go to the foreman from the salon near the park. The hairdresser does not cut his own hair, and if there is only one master in the village besides him, then, probably, it was he who made a mess on the head of his colleague! But for another, the hairstyle is perfect - which means that it is worth choosing the master who made it.

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– 7 –

What doesn't happen once a year, but happens twice in every month, three times in every week, and once every weekend?

The letter "e".

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– 8 –

The conference of tall people is attended by 25 people. If each of those present shakes hands only with the one who is shorter than him, how many handshakes will take place?

Nobody will shake hands with anyone, because people should only shake hands with those who are lower. But for this to happen, the one below must break the rule.

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– 9 –

Let's say you have four coins.

You can select and move any of them. Don't be lazy - go for real coins from your wallet to solve the puzzle. And the challenge is: can you place four coins so that each one touches all the others at the same time?

This puzzle may not be a challenge for you, but it may come as a surprise. Suffice it to say: she has a solution.

The solution is for three coins to touch, forming a triangular shape, and the fourth to lie on top. As easy as pie!

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– 10 –

I live in the city, but between the last sunset and sunrise I went to bed and got out of it a staggering number of times - 90. In addition, I managed to sleep 7 hours before each rise. At the same time, I am not at all a lover of sleep. How did I manage this?

I live in Iceland's capital Reykjavik, where the sun never sets in summer. You can also think about some settlements in the Far North.

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– 11 –

Six people are standing in the room. Each takes turns talking to you. They conclude their statements with the following phrases, speaking them to you one by one in this order:

• Person A: One person is definitely lying.
• Person B: two are definitely lying.
• Person C: Three are definitely lying.
• Person D: Four are definitely lying.
• Person E: Five are definitely lying.
• Person F: We all lie.

Which of these people, A through F, told you the truth (if anyone did)?

All persons from A to D lie, because in each case it is necessary that at least two people tell the truth, but no two people say the same thing, they all contradict each other. Person F is probably lying, because if everyone was telling the truth, they would be contradicting themselves.

This means that we are left with person E. Person E cannot lie, because if the speakers were lying, then either everyone would be lying, and this means that person E is telling the truth (and we know that this is impossible), or someone from A before D would be telling the truth, which is also impossible. So E is telling the truth and everyone else is lying.

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– 12 –

Two children went to explore the area. At some point, they have to go through a cave, which is located behind the thickets on the nearest hill. Neglecting the parents' order not to do stupid things, the children rush into the cave without hesitation.

It is dark in the cave, and none of the children have a torch, so they cannot see where they are going. One of them is significantly ahead of the other and raises a cloud of coal dust where, apparently, there was an open adit earlier. Frightened by a sudden obstacle, the children rush out of the cave, screaming in horror and delight.

Once out into the open air, both rush straight to their homes. The child who stumbled upon a pile of coal has a dirty face, but when he comes home, he is not going to wash. The other has a completely clean face, but when he gets home, he immediately rushes to the sink and violently rubs his face.

Knowing that none of the children usually tried to wash when they came home, and also that their current behavior is absolutely no coincidence, what reasonable explanation can be given to him?

A child with a clean face saw his grimy friend run out of the cave. Therefore, running home, he first rushed to wash, as he decided that his face was dirty too.

On the contrary, a child with a dirty face saw his companion run out of the cave with a completely clean face. Since it was dark in the cave, he did not understand that his face was smeared with coal dust, and therefore, having reached the house, he did not even think to go to wash.

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– 13 –

Recently my mother gave me a couple of cufflinks that she inherited from her father. I know that another mother also gave a pair of inherited cufflinks to her child. But we are talking about the same pair of cufflinks. How can this be?

The other mom is me, and I passed the cufflinks that I just inherited to my child.

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– 14 –

I took my watch to the jeweler for repair, but when I got it back, I see that something is wrong with it. When it should be 3:30, they show 6:15, when it should be 4:45, they show 9:20. What's wrong with my watch?

After the repair, the hands on the watch were set differently, so that the large hand points where the small hand should point, and vice versa.

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– 15 –

You are in a holiday home in a secluded area. All electric lights are off. You cannot light them, and you have no other way to light up the surrounding space. Nevertheless, you can see everything perfectly, walking around the house. Although you don't have a night vision goggle or anything like that. How is this possible?

It's a clear day now, so no additional lighting is required - the sun is shining.

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More riddles and puzzles with detailed answers can be found in the book "Lateral Logic".