In one game, a player can defeat another by choosing something that breaks it. However, the same player loses if the opponent chooses something that covers it.
Question: What three-object game is being described?
Rock, paper, scissors.
You enter a dark room. There is a candle, an oil lamp, and a fireplace. You have only one match.
Question: What do you light first?
The match.
A man stands in heavy rain without an umbrella or hat. His clothes become soaked, but his hair remains completely dry.
Question: Why?
He is bald.
The more you take from it, the bigger it becomes.
Question: What is it?
A hole.
A clock takes five seconds to strike six times. Assume the time between strikes is constant.
Question: How long does it take to strike twelve times?
11 seconds. Six strikes create five intervals; twelve strikes create eleven intervals.
A person can break one of these without touching it. They can also keep one without putting it in a box. Once broken, it may change an entire relationship.
Question: What is it?
A promise.
A farmer has 15 sheep. All but 8 escape.
Question: How many sheep remain?
Eight
A person enters a restaurant and asks for water. Instead of giving water, the waiter suddenly shouts loudly. The customer thanks the waiter and leaves.
Question: Why might the customer be grateful?
The customer had hiccups, and the sudden shock stopped them.
It belongs to you, but other people use it more often than you do.
Question: What is it?
Your name.
A student answers every question on an exam correctly, but the teacher gives the student zero points.
Question: Give one logically possible explanation.
Answer: The student answered correctly but submitted the exam after the deadline, and the rules specify that late submissions receive zero. Other answers are acceptable if they fit the conditions.
A person uses it to see something that cannot be seen directly. However, the more accurately it reflects the original, the less original it becomes.
Question: What is it?
A reflection.
Three boxes contain apples, oranges, or a mixture of both. The boxes are labeled “Apples,” “Oranges,” and “Mixed,” but every label is wrong. You may take one fruit from one box without looking inside.
Question: Which box should you choose to identify all three boxes?
Answer: Choose the box labeled “Mixed.” Since its label is wrong, it must contain only apples or only oranges. The fruit you draw identifies that box, and the other two can then be identified by elimination.
A person is looking at a photograph. They have no siblings. They say, “The father of the person in this photograph is my father’s son.”
Question: Who is in the photograph?
Their son.
It can travel around the world while remaining in one corner.
Question: What is it?
A postage stamp.
A person says, “I always lie.”
Question: Can this statement consistently be classified as simply true or false?
Answer: Not under the usual interpretation. If it is true, the speaker is lying, so it is false. If it is false, the speaker does not always lie, which does not establish that this particular statement is true. The wording alone does not give enough information to determine the speaker’s general truthfulness.
One person gives it away and becomes richer in another sense. Another person receives it but cannot keep it forever. It can be shared by thousands without being divided into pieces.
Question: What is it?
Knowledge.
Three people—A, B, and C—make the following statements:
Exactly one person is telling the truth.
Question: Who is telling the truth?
Answer: C.
If C is telling the truth, A and B are both lying. A’s statement is false, and B’s statement is false because C is truthful. Therefore, exactly one statement is true.
A prisoner is told: “If your next statement is true, you will be imprisoned. If it is false, you will be released.”
Question: What could the prisoner say to make the rules logically inconsistent?
Answer: “I will be released.”
If the statement is true, the prisoner must be imprisoned, making the statement false. If it is false, the prisoner must be released, making the statement true.
It has cities but no houses, forests but no trees, and rivers but no water.
Question: What is it?
A map.
A university has two students. One always tells the truth, and the other always lies. You do not know which is which. One door leads to safety, and the other leads to danger. You may ask one student one yes-or-no question.
Question: What question guarantees that you choose the safe door?
Answer: Ask either student: “Would the other student tell me that the left door is safe?” If the answer is yes, choose the right door; if the answer is no, choose the left door.
It can be created in seconds but take years to repair. It can exist between two people who have never met, and one action can destroy what thousands of actions built.
Question: What is it?
Trust
You have 12 coins that look identical. One is counterfeit and is either heavier or lighter than the others. You have a balance scale and can use it only three times.
Question: Can you identify the counterfeit coin and determine whether it is heavier or lighter?
Answer: Yes. A carefully designed sequence of three weighings can distinguish all 24 possibilities: 12 coins × 2 possibilities (heavier or lighter). Each weighing has three possible outcomes, giving up to 27 outcome patterns. The challenge is to design a valid weighing strategy that distinguishes every possibility.
You are outside a closed room with three switches. Inside the room are three traditional light bulbs, each controlled by a different switch. You cannot see the bulbs from outside, and you may enter the room only once.
Question: How can you determine which switch controls each bulb?
Answer:
The illuminated bulb belongs to the second switch. The unlit but warm bulb belongs to the first switch. The unlit, cool bulb belongs to the third switch.
The first person creates it, the second person buys it, and the third person uses it without knowing it.
Question: What is it?
A coffin.
A company has 100 employees. Every employee believes that at least one other employee is making a serious mistake, but nobody knows whether anyone else has noticed it. The manager publicly announces that at least one employee is making the mistake. Everyone can observe the situation perfectly and reason logically, but employees cannot communicate with one another.
Question: What additional information would you need before predicting when the employees will correct the mistake?
Answer: You would need to know the precise rules governing how employees recognize the mistake, what actions they take based on that knowledge, and whether the manager’s announcement creates common knowledge. Without those details, the timing cannot be determined.