A traveller comes to a fork in the road which leads to two villages. In one village the people always tell lies and in the other village the people always tell the truth. The traveller needs to conduct business in the village where everyone always tells the truth. A man from one of the villages is standing in the middle of the fork, so there is no indication of which village he comes from. The traveller approaches the man and asks him just one question. From the man's answer, he knows which road to follow.
What did the traveller ask?
The King is about to die. He sends messengers throughout the land looking for the three smartest people. Finally, three are found. He gives them a task to see which one is the wisest. He tells them, "I will seat you in a triangle so that each of you faces the other two. Then I will blindfold you and paint either a yellow or a blue dot on each of your foreheads. When I remove the blindfolds you must each raise your hand if you see any yellow dots. As soon as you have worked out what colour your own dot is, lower your hand and tell me." So he seats them, blindfolds them, and then paints a yellow dot on all three foreheads. When the blindfolds are removed, all three hands go up. After a long pause, one hand comes down and the man says, "Your Highness, I have a yellow dot." How did he know?
You are visiting an island on which two tribes of natives live. One tribe has black soles and always lies; the other tribe has white soles and always tells the truth. There are three natives standing near you. You can't see the bottoms of their feet, and indeed you find out it is extremely rude to look at another's soles, but you are curious so you ask the first man, "Sir, what colour are your soles?" Now he happens to understand English, but he can't speak it, so he replies in his native tongue, "Glub Glub." You turn to the second man and ask, "Sir, what did he say?" The second man replies, "He said he has white soles." Now to be sure, you turn to the third and ask, "Sir, what colour soles does this second man have?" The third man replies, "Sir, he has black soles." Now the question is, what colour are the third native's soles?
You are travelling in a deep, dark forest and get lost. A trapdoor suddenly opens and you fall down into a dark chamber. You hear a voice, "You are trespassing and the penalty is death. In five minutes you will be buried alive. However, due to our exceeding kindness and mercy, we will allow you to earn your life back. In this dark chamber there are two doors. You may choose to open either one - if you choose correctly, you will go free. If you choose incorrectly, well, then your fate has not changed and you will still be buried alive. To help you choose, you may ask a question. However, you should know that two people will hear you; one of them always lies and the other one always tells the truth. One of them will answer your question, but you will not know which one. They both know which door leads to freedom. Good luck, you have four and a half minutes left." What question do you ask to win your freedom? (At least two solutions.)
What are the answers?
A man comes home from work by train every day. He gets to the train station at 5 pm and
from there his dog picks him up in the car. One day the man arrived at the station at 4 pm
and decided to start walking and meet his dog somewhere between the train station and
home. His dog drove the car as usual, met him on the road before reaching the station, and
took him home. That day, they got home 20 minutes early.
How long had the man been walking?
1. In the forest, a hotel has an infinite number of rooms. An infinite number of forest
people arrive and each takes a room. So far, so good. Now you would like a room.
Can the hotel accommodate you? If so, how?
2. The hotel has an infinite number of rooms. An infinite number of forest people arrive
and each takes a room. So far, so good. Now another infinite number of guests arrive.
Can the hotel accommodate them all? If so, how?
You are on an island and you see a forest person ploughing a field with a large
tractor. There are no bridges or tunnels to the island and you wonder how the tractor got
out to the island.
"That's a good question," says a nearby forest person, reading your mind.
"I have the only boat around here and it's not big enough to carry that tractor over.
I didn't drop off any parts, either, so he couldn't have built it there. And no one has an
airplane or helicopter to drop it off."
So how did the tractor get on the island?
(Notes: 1. the tractor was not built on the island
2. even with tides, the water is too deep to drive across
3. it was not driven across the bottom of the ocean or under water
4. it was not disassembled)
The Hatter opened his eyes very wide on on hearing this; but all he said was, "Why is a raven like a writing-desk?"... "Have you guessed the riddle yet?" the Hatter said, turning to Alice again. "No, I give it up," Alice replied. "What's the answer?" "I haven't the slightest idea," said the Hatter.
Answer
There is an island that is considered to be paradise. All the inhibitants of the island are Perfect Logicians, and every knows of every that they are Perfect Logicans. Exactly 100 of these persons have blue eyes, 100 have brown eyes, and 1 has green eyes. The inhibitants do not know what his/her color eyes is. Everyone is constantly aware of everyone elses eye color but no person knows that there are 100 blue eyed, 100 brown eyed, and 1 green eyed person on the island. If a person finds out his/her own eye color she/he must leave the island at midnight of the day she/he finds out! There are no mirrors or reflections of any kind on the island. Also, nobody on the island ever speaks except the Guru, who is the person with the green eyes, (she does not know her eye color and if she found out she would have to leave the island at midnight). The Guru says one sentence every fifty years. One day the Guru arrives and tells everyone on the island the following: I SEE SOMEONE WITH BLUE EYES. Who (if anyone) leaves the island and when?
Answer
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