An island is inhabited by two classes of people: knights, who make only true statements, and knaves, who make only false statements. Three inhabitants are conversing. Alfred says, "All of us are knaves." Bert says, "Exactly one of us is a knight." What are Alfred, Bert, and Charles?
The Clinton Brothers (Bill and Ben) are identical twins. Ben is known to be totally truthful, and the other is a politician. You meet one of them at a fork in the road, and there's no sign to indicate which is the road to Washington (your destination). What single question can you ask the brother who is there, to discover the correct road? Assume that you don't know if it's Bill or Ben, and that politicians always lie...
Looking at a portrait, a man said "Brothers and sisters have I none, but that man's father is my father's son." Whose portrait is it?
Which of the following statements is true?
Exactly one of these ten statements is false.
Exactly two of these ten statements are false.
Exactly three of these ten statements are false.
Exactly four of these ten statements are false.
Exactly five of these ten statements are false.
Exactly six of these ten statements are false.
Exactly seven of these ten statements are false.
Exactly eight of these ten statements are false.
Exactly nine of these ten statements are false.
Exactly ten of these ten statements are false.
What happens if you remove the word 'Exactly' from all the statements?
An Arab sheikh tells his two sons to race their camels to a distant city to see who will inherit his fortune. The one whose camel is slower will win. The brothers, after wandering aimlessly for days, ask a wise man for advise. After hearing the advice they jump on the camels and race as fast as they can to the city. What does the wise man say?
You are a biochemist, working with a 12-slot centrifuge. This is a gadget that has 12 equally spaced slots around a central axis, in which you can place chemical samples you want centrifuged. When the machine is turned on, the samples whirl around the central axis and do their thing.
To ensure that the samples are evenly mixed, they must be distributed in the 12 slots such that the centrifuge is balanced evenly. For example, if you wanted to mix 4 samples, you could place them in slots 12, 3, 6 and 9 (assuming the slots are numbered from 1 to 12 like a clock).
Problem: Can you use the centrifuge to mix 5 samples?
How many flowers do I have if all of them are roses except two, all of them are tulips except two, and all of them are daisies except two?
You want to send a valuable object to a friend. You have a box which is more than large enough to contain the object. You have several locks with keys. The box has a locking ring which is more than large enough to have a lock attached. But your friend does not have the key to any lock that you have. How do you do it? Note that you cannot send a key in an unlocked box, since it might be copied.
Start with a half cup of tea and a half cup of coffee. Take one tablespoon of the tea and mix it in with the coffee. Take one tablespoon of this mixture and mix it back in with the tea. Which of the two cups contains more of its original contents?