Two Japanese people who have never seen each other meet at the New York Japanese Embassy. They decide to have drinks together at a nearby bar. One of them is the father of the other one's son. How is this possible?

The Japanese are husband and wife and both blind since birth.

You have two lengths of rope. Each rope has the property that if you light it on fire at one end, it will take exactly 60 minutes to burn to the other end. Note that the ropes will not burn at a consistent speed the entire time (for example, it's possible that the first 90% of a rope will burn in 1 minute, and the last 10% will take the additional 59 minutes to burn).
Given these two ropes and a matchbook, can you find a way to measure out exactly 45 minutes?

The key observation here is that if you light a rope from both ends at the same time, it will burn in 1/2 the time it would have burned in if you had lit it on just one end.
Using this insight, you would light both ends of one rope, and one end of the other rope, all at the same time. The rope you lit at both ends will finish burning in 30 minutes. Once this happens, light the second end of the second rope. It will burn for another 15 minutes (since it would have burned for 30 more minutes without lighting the second end), completing the 45 minutes.

You are walking down a path when you come to two doors. Opening one of the doors will lead you to a life of prosperity and happiness, while opening the other door will lead to a life of misery and sorrow. You don't know which door leads to which life.
In front of the doors are two twin brothers who know which door leads where. One of the brothers always lies, and the other always tells the truth. You don't know which brother is the liar and which is the truth-teller.
You are allowed to ask one single question to one of the brothers (not both) to figure out which door to open.
What question should you ask?

Ask "If I asked your brother what the good door is, what would he say?"
If you ask the truth-telling brother, he will point to the bad door, because this is what the lying brother would point to.
Alternatively, if you ask the lying brother, he will also point to the bad door, because this is NOT what the truth-telling brother would point to.
So whichever door is pointed to, you should go through the other one.

You walk into a creepy house by yourself. There is no electricity, plumbing or ventilation. Inside you notice 3 doors with numbers on them. Once you open the doors you will die a particular way.
Door #1 You’ll be eaten by a lion who is hungry.
Door #2 You’ll be stabbed to death.
Door #3 There is an electric chair waiting for you.
Which door do you pick?

Door #3, Since There Is No Electricity To Harm You.

Betty signals to the headwaiter in a restaurant, and says, "There is a fly in my tea."
The waiter says "No problem Madam. I will bring you a fresh cup of tea."
A few minutes later Betty shouts, "Get me the manager! This is the same cup of tea."
How did she know?
Hint: The tea is still hot.

Betty had already put sugar in her tea before sending it back. When the "new" cup came, it was already tasted sweet.

On the first day of the school a young girl was found murdered. Police suspect four male teachers and question them. They were asked what they were doing at 8:00 am.
Mr. Walter: I was driving to school and I was late.
Mr. Thomas: I was checking English exam papers.
Mr. Benjamin: I was reading the newspaper.
Mr. Calvin: I was with my wife in my office.
The police arrested the killer. How did the police find the murderer?

Mr.Thomas as he cannot be checking exam papers on the first day of school.

As I was going to St. Ives
I met a man with seven wives
The seven wives had seven sacks
The seven sacks had seven cats
The seven cats had seven kits
Kits, cats, sacks and wives
How many were going to St. Ives?

One person is going to St. Ives (the narrator). Because the narrator "met" all of the others mentioned in the poem, this implies that they walked past each other in opposite directions, and thus none of the wives, sacks, cats, or kits was actually headed to St. Ives.
If you (like many) think this answer is a bit silly, you can assume that all the people, sacks, and animals mentioned were heading for St. Ives. In this case, we would have 1 narrator + 1 man + 7 wives + 49 sacks + 343 cats + 2401 kits = 2802 total going to St. Ives. However, this isn't the traditional answer.

An egg has to fall 100 feet, but it can't break upon landing (or in the air). Its fall can't be slowed down, nor can its landing be cushioned in any way. How is it done?

Drop it from more than 100 feet high. It won't break for the first 100 feet.

Sam has got three daughters. The eldest daughter is the most honest girl in the universe and she always speaks truth. The middle daughter is a modest woman. She speaks truth and lies according to the situations. The youngest one never speaks truth. Not a single word she spoke was true and would never be true.
Sam brought a marriage proposal for one of his girls. It was John. John wanted to marry either the eldest or the youngest daughter of Sam as he can easily identify whether the girl speaks truth or lie!
John told his desire to Sam. However, Sam laid a condition. He told John that he will not say who the eldest, middle or youngest one is. Also, he allowed John to ask only one question to identify the eldest or youngest so he can marry one.
John asked one question and found the right girl. What was the question and whom should he pick?

The question he asked is, 'Is she older than her?'
He asks this question to one of the daughters.
If he asked this question to older daughter pointing at other two, he probably would know the youngest one! NO matter, she always speaks truth.
If he asked the question to middle one, probably he can choose either.
If he asked the youngest one, she always lies and he can find eldest one. No matter, he has to choose the youngest one based on the answer.

On the game show et´s Make a Deal, Monty Hall shows you three doors. Behind one of the doors is a new car, the other two hide goats. You choose one door, perhaps #1. Now Monty shows you what´s behind door #2 and it´s a goat.He gives you the chance to stay with original pick or select door #3. What do you do?

You should always abandon your original choice in favor of the remaining door (#3). When you make your first choice the chance of winning is 1 in 3 or 33%. When you switch doors, you turn a 2 in 3 chance of losing in the first round into a 2 in 3 chance of winning in the second round.
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