Medium – Puzzle Prime

Buried Up to Neck

Section: Brain Teasers Category: Deduction

Difficulty: Medium

Three friends, Adam, Bob, and Charlie are buried in the sand up to their necks, all facing West. Charlie can see both Adam and Bom, Bom can see only Adam, and Adam cannot see anyone. Black and white hats are placed on their heads. The three friends are told that there is at least one hat from each color, and then they are asked whether anyone can guess the color of their own hat.

After a few minutes, one of them answers. Who is that?

SOLUTION

If Adam and Bob had hats with identical colors, then Charlie would immediately be able to deduce that his hat has the opposite color. Charlie doesn’t do that, so Adam and Bob are able to figure out that their hats have opposite colors. Since Bob is the one who can see the color of Adam’s hat, he is the one that answers the question.

Unknown Author February 13, 2024

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Least Likely

Section: Brain Teasers Category: Insight

Difficulty: Medium

Sarah lives in the UK. Which of these statements is least likely:

Sarah speaks English.
Sarah eats baby pandas.
Sarah speaks English and eats baby pandas.

SOLUTION

The answer is 3. This is because statements 1. and 2. are more general than statement 3. and therefore more likely to be true.

Unknown Author January 28, 2024

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Ancient Coins

Section: Brain Teasers Category: Insight

Difficulty: Medium

Suppose I show you two ancient coins. The first one is dated 51 B.C., the second one is marked George I. Which one is counterfeit?

SOLUTION

Both of them. People who lived 51 years before Christ didn’t know about Jesus yet. When King George I was ruling, he was the first king with this name, and so he was just called George.

Unknown Author January 10, 2024

1 Comment

Third Business Day

Section: Brain Teasers Category: Deduction

Difficulty: Medium

What is the chance that the third business day of a month is Wednesday?

SOLUTION

Assuming there is an equal chance that the given month begins with any of the seven days of the week, the answer is 3/7. That’s because Saturday and Sunday are non-working days, and therefore if the month starts with any of them, the third business day will still be Wednesday.

We note that 3/7 is actually an approximation of the actual answer, since the frequencies with which the days of the week appear as first in a given month, are close to but not equal to 1/7 each.

Unknown Author December 28, 2023

2 Comments

Ping Pong Ball

Section: Brain Teasers Category: Insight

Difficulty: Medium

Your last ping pong ball falls down into a narrow pipe embedded in concrete one foot deep. How can you get it out undamaged if all you have is your tennis paddle, your shoelaces, keys, wallet, and a plastic water bottle, which does not fit into the pipe?

SOLUTION

Using the plastic bottle, pour water into the pipe so that the ball will rise up.

Unknown Author December 19, 2023

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Chase on a Horse’s Back

Section: Casual Puzzles Category: Maze

Difficulty: Medium

You are chasing a thief on the back of a horse on a (ruined) chessboard. You must traverse the maze by using only knight’s movements, but be careful – pieces can destroy each other.

SOLUTION

The solution is shown below.

Johann Sturcz December 13, 2023

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Fathers, Sons, and Fish

Section: Brain Teasers Category: Insight

Difficulty: Medium

Two fathers and two sons went out fishing. Each of them catches two fish. However, they brought home only six fish. How so?

SOLUTION

They were a son, his father, and his grandfather – 3 people in total.

Unknown Author December 10, 2023

1 Comment

Glow and Shine

Section: Brain Teasers Category: Insight

Difficulty: Medium Tags: Words

There is a property that applies to all words in the first list and to none in the words in the second list. What is it?

GLOW, ALMOST, BIOPSY, GHOST, EMPTY, BEGIN
SHINE, BARELY, VIVISECTION, APPARITION, VACANT, START

SOLUTION

The words in the first list are called “Abecederian”, i.e. their letters are in alphabetical order.

Unknown Author November 13, 2023

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Escaping the Kingdom

Section: Brain Teasers Category: Insight

Difficulty: Medium

A long time ago there was a kingdom, isolated from the world. There was only one way to and from the kingdom, namely through a long bridge. The king ordered the execution of anyone caught fleeing the kingdom on the bridge and the banishment of anyone caught sneaking into the kingdom.

The bridge was guarded by one person, who was taking a 10-minute break inside his cabin every round hour. Fifteen minutes were needed for a person to cross the bridge and yet, one woman managed to escape the kingdom. How did she do it?

SOLUTION

Once the guard entered the cabin, the woman started crossing the bridge for 9 minutes, and then turned around and pretended to be going in the opposite direction for one more minute. When the guard caught her, she said she was trying to enter the kingdom, so he banished her away.

Unknown Author November 1, 2023

3 Comments

Unconscious and Bleeding

Section: Brain Teasers Category: Lateral

Difficulty: Medium

A man is found unconscious in front of a store at two in the morning. His head is bleeding and there is a brick laying next to him. When the police arrive, they carry the man to jail. Why did they arrest him?

SOLUTION

The man was a burglar who tried to break the store’s glass with the brick. The glass turned out to be bullet proof, so the brick bounced back and hit him in the head, knocking him out.

Unknown Author October 25, 2023

1 Comment