Unfaithful

Jack is looking at Anne, but Anne is looking at George. Jack is married, but George is not. Is a married person looking at an unmarried person?

  • Yes
  • No
  • Cannot be determined 

Invisible King

The white king has made himself invisible. Where is he?

Move Move Chess

Consider a chess game in which every player is allowed to move twice per turn. Show that Black does not have a winning strategy.

Codex Enigmatum

These are a few enigmas from the puzzle book CODEX ENIGMATUM. What is the answer to puzzle #9?

Source:

Codex Enigmatum by Rami Hansenne

Moms’ Talk

Two moms, Sarah and Courtney, are talking to each other.

Sarah: I have two children.
What is the probability that both of Sarah’s children are boys?

Courtney: Me too! Do you have any boys?
What is the probability that both of Courtney’s children are boys?

Sarah: Yes, I do! What is your younger child?
What is the probability that both of Sarah’s children are boys?

Courtney: It is a boy. He is so mischievous!
What is the probability that both of Courtney’s children are boys?

Sarah: Is he Sagittarius? Sagittarius boys are known to drive their mothers crazy. I can testify from personal experience.
What is the probability that both of Sarah’s children are boys?

Courtney: No, but actually I have the opposite personal experience to yours.
What is the probability that both of Courtney’s children are boys?

Sarah: Well, I guess astrology does not always get it right.

Courtney: I assume it does about half of the time.

10 Pounds of Flour

You have a big bag of flour, two 5lbs weights, and an inaccurate balance scale. How can you measure exactly 10lbs of flour?