Linked Questions

8
votes
3answers
2k views

In the blue-eyes puzzle, why can't they skip ahead? [duplicate]

In the solution to the Blue Eyes logic puzzle, there is a follow-up question: Each person knows, from the beginning, that there are no less than 99 blue-eyed people on the island. How, then, is ...
1
vote
0answers
7k views

An illness at a monastery [duplicate]

In Faraway Land there is a monastery built atop a mountain in which monks live isolated from the rest of the world. The monastery is made of two large buildings: one is where the monks sleep, the ...
0
votes
0answers
186 views

The Green-Eyed Dragons Riddle [duplicate]

You visit a remote desert island inhabited by one hundred very friendly dragons, all of whom have green eyes. They haven't seen a human for many centuries and are very excited about your visit. They ...
0
votes
0answers
144 views

How many cheating husbands? [duplicate]

There is a matriarchal town which believes that a prophetic stranger will tell the wives whether any of the husbands are cheating. The stranger will only say yes if there are any and no if there are ...
3
votes
0answers
114 views

Magical election of novices in a monastery [duplicate]

In a monastery, there is a special rite to elect new novices. All candidates (we're talking of a huge number, so let's assume an infinite amount) gather together in one hall that gets locked, so that ...
0
votes
0answers
47 views

Is it necessary to state that there is a logician with a blue hat in this 100 logicians puzzle? [duplicate]

I've been discussing the logic puzzle where 100 logicians, all wearing blue hats, are trapped in a room and told: they can leave when a bell rings if they know they know they are wearing a blue hat, ...
22
votes
2answers
3k views

The Dwarves' Test

One day, the chief of the dwarves decided he wanted to test his tribe. So that night, he told the dwarves that he would paint on each dwarf's back a dot colored either red or blue. Each dwarf will ...
17
votes
6answers
2k views

Abby and Bobby and three numbers on the blackboard

Abby selects a non-negative integer $A$, and Bobby selects a non-negative integer $B$. They then both tell their number secretly to Summy. Summy writes the numbers $5$, $8$, and $15$ on the ...
11
votes
6answers
6k views

Who has mud on their forehead?

This is probably my favorite puzzle. It uses logic, but it's not one of those "logic table" puzzles which i dislike immensely. What is this type of puzzle called and are there more like it that are ...
12
votes
8answers
2k views

The Dot-town suicide

Each resident of Dot-town carries a red or blue dot on his (or her) forehead, but if he ever figures out what color it is he kills himself. Each day the residents gather; one day a stranger comes and ...
7
votes
2answers
855 views

Green Eyed Oracle Variant - Not a Multiple of $17$

$100$ perfect logicians have been gathered on an island. It is common knowledge that logicians always have blue or brown eyes, though on this island, all eyes are blue. However, there are no ...
4
votes
2answers
451 views

Variant to blue eyes puzzle - selfish logicians

This is a variation of the blue eyes puzzle. Suppose the logicians want to get off the island. They are selfish and think only of themselves. They may help others as well, but solely for their own ...
1
vote
1answer
156 views

Mensa 3rd Grade Recess Game [closed]

Mensa 3rd Graders At Recess There are dozens of variations of this puzzle type, but I put my own spin and characteristics to it. It is lunch time for the little ones at Mensa Mini's Private School. ...
0
votes
1answer
186 views

The king riddle [duplicate]

I think I have seen a nice riddle that you may like. (This riddle has been translated so I hope that no valuable information has been lost): Two friends walk in distant lands when they are trapped ...