Riddle: Test your Logic Skills

image_pdfimage_print

Suppose you are visiting an island with knights who always tell the truth, knaves who always lie, and jokers who can do either.

You meet three islanders named  Theodore, Alvin and Simon. They all know what the others are (a knight, knave, or joker) and make the following statements:

If exactly one of them is a joker, how many of them are knights?

Choices:

  1. One of them
  2.  Two of them
  3. None of them


Correct Answer: One of them is a knight.

Since exactly one of them is a joker and they all accuse different people of being jokers, the joker is lying. If the joker were telling the truth, then they would claim that they themselves are the joker, which none of these three are doing.

Given each person is accused by another, one of them is correctly accusing the joker of being a joker and thus is telling the truth. For instance, suppose that Theodore is the Joker. Then Simon is telling the truth. Or you can suppose that Alvin is the joker, in which case Theodore is telling the truth.

This person telling the truth can’t be a joker (since as already pointed out, the joker is lying), so the truth-teller must be a knight.

We’ve concluded that one person is a joker and at least one is a knight. The third person can’t be a knight (they must be a knave), because the knight and the third person are saying that different people are jokers, which is impossible with only one joker. For instance, if Theodore is the joker, then Simon is telling the truth (and is a knight) and Alvin is lying (and is a knave).

So, since there is only one truth-teller, there must be only one knight.

Note: “None of them are knights” is incorrect because one of them is a joker and all of them point to another person as the joker. One of them has to be telling the truth, and it’s not the joker.

 

Spread the love
No Comments Yet

Leave a Reply

Your email address will not be published.

Write to us at
mail@currentkids.in

Help us keep currentkids, current! We’d love to hear about your crazy adventures and experiences. Send us your pictures, travel diaries, thoughts on cool new gadgets, gaming experiences and anything else you find interesting!

About Us

Welcome to our entertaining and empowering news source for kids with inquisitive minds! This is a digital space that keeps kids aged 8 and above (and your families!) connected to what’s happening in the world. We filter a wide variety of news, events, and interesting bits of trivia to develop short, relevant, unbiased content in creative formats. We give everyone something to relate to and get engaged with in short bytes of information with a snappy, chatty feel. We believe in encouraging curiosity, creativity and continued learning in our safe digital space.

Why is reading non-fiction important?

This helps curious minds to learn more about the outside world. It also enriches their vocabulary and their general knowledge. Simplified news helps children to express their opinions easily with their friends and family and gives them some perspective on complex issues. Our safe news website will give you parents a useful tool with which to navigate the digital world with your children.

We hope you enjoy our posts!

Biyash & Sunaina