Saturday, February 17, 2018

A Knight, a Knave, and a Spy


You find yourself on the Island of Knights, Knaves, and Spies, a logical kingdom whose inhabitants always lie (Knaves), always tell the truth (Knights), or who can do either (Spies). You encounter three of said inhabitants, call them Alice, Bob, and Carol. You are told by your guide (a trustworthy Knight) that in this group there are one of each type of inhabitant, a Knight, a Knave, and a Spy. You ask the following questions.

To Alice you ask, "Are you a Knight?"

"No," she answers.

To Bob you ask, "Are you a Spy?"

"No," replies Bob.

Finally, you ask Carol, "Are you a Knave?"

"No," she says.

Can you tell from these answers who is a Knight, who is a Knave, and who is a Spy? Click below for the answer.


Saturday, February 10, 2018

The King's Adviser


A king decides he is going to fire one of his advisers. He tells him that he has written "You're fired" on one slip of paper, and "You can stay" on another, and that the adviser is to choose one at random. The king has secretly written "You're fired" on both notes, but unbeknownst to the king, the adviser has found this out! How can the adviser keep his job without telling the king that he knows both notes are the same?


Saturday, February 3, 2018

Water Glasses


You have five glasses arranged in a row. The first two are empty and the last three are filled with water. By moving only one glass, can you arrange them so full and empty glasses alternate? Click below for the answer.





Saturday, January 27, 2018

Knights or Knaves?


You find yourself on the Island of Knights and Knaves, a logical kingdom whose inhabitants either always lie (Knaves) or always tell the truth (Knights). You encounter three of said inhabitants, call them Alice, Bob, and Carol. You ask the following questions.

To Alice you ask, "Is Bob a Knight or a Knave?"

"A Knight," she answers.

To Bob you ask, "Are Alice and Carol both Knights or both Knaves?"

"Yes," replies Bob.

Finally, you ask Carol, "Is Bob a Knight or a Knave?"

"A Knave," she says.

Who is a Knight and who is a Knave? Click below for the answer.


Saturday, January 20, 2018

True or False?


You're taking your college entrance exam, and things are not going well. You spent too much time answering the essay questions and word problems, and now you're running out of time. You turn to the final section and are relieved to find that it consists of 100 True/False questions. The bad news is that you only have 2 minutes left to complete the entire exam!

You figure it doesn't matter if you answer all True, all False, or just guess randomly. Odds are you'll probably get half of them right either way. You begin scribbling in your answers.

How many different ways (unique sequences) are there to answer 100 True/False questions? Click below for the answer.


Saturday, January 13, 2018

King's Sentence


A man is caught poaching on the King's property. He is brought before the King to be sentenced.

The King says, "You must give me one statement. If it is true, you will killed by lions. If it is false, you will be killed by trampling of wild buffalo."

In the end, the King has to let the man go.

What was the man's statement? Click below to see the answer.



Saturday, January 6, 2018

A Boy and a Girl


Two children, one boy and one girl, make the following statements.

"I am a boy" said the child with brown hair.

"I am a girl" said the child with red hair.

At least one of the children is lying. Who is the boy and who is the girl? Click below for the answer.