# Questions tagged [logical-deduction]

A puzzle that requires formal logical deduction to arrive at the solution. This suggests more than merely reasoning through clues to find an answer (you might want [situation] for that).

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### How Many Queens to Threat Themselves?

How many queens can be placed in a standard $8*8$ chessboard to threat each of them exactly once by other queens?
1answer
810 views

### The knaves come out at night

Standard knights and knaves problem. There are 10 people in a room, you know that each person will either always tell the truth or always lie, but you don't know who is a truth teller or liar. You ...
3answers
2k views

### How do I solve the “Between Worlds” Android puzzle game?

I've been struggling for a while with the Between Worlds Android game, and have not yet solved it. I've only noticed a couple vague properties that hold in localized cases. To operate the puzzle, ...
3answers
2k views

### A square and a circle at once [closed]

Can you draw something on a piece of paper that looks like a square and a circle at the same time? ( without using Math or 3-d visualisation techniques)
1answer
295 views

### The Moving Bots

Each of the 50 robots move around in a room. The room is 8 by 8 tiles long. Each bot takes up 1 tile. On each turn they move like the knight in Chess, they don't teleport, they move. They all move at ...
1answer
1k views

### Clue for the Treasure Hunter

One day a treasure hunter was searching for treasure on an abandoned island. He got tired of looking everywhere, so he walked towards a big tree that he saw in order to rest in its shade. As he ...
1answer
484 views

### Val, Lynn Chris

This is taken from a riddle book: Val, Lynn and Chris are related to each other, but no incestuously. Among the three are Val's father, Lynn's only daughter, and Chris' sibling. Chris' sibling is ...
3answers
805 views

### Searching for gold

You are a treasure hunter in search of the legendary gold of the Isle of Goon. According to your research the gold is buried either behind the old church, or under the giant palm tree. You travel to ...
2answers
2k views

### Unknown Consecutive Integers Puzzle

Two people, Anne and Bob, each hold an index card. A positive integer is printed on each index card, and these integers are consecutive (i.e. Anne's card may display 8 and Bob's card 7). Anne and Bob ...
1answer
270 views

### Non-Diagonal Pointing Problem

You can see the rules for pointing problem at this article. It has been clarified that there is no solution to this question. But, what if we remove the diagonal rule? is there any solution?
2answers
563 views

### How to let all people in Group A talk to all people in Group B in a shortest amount of time?

Ok, let say Group A has N number of people, and Group B has M number of people. I want each person in Group A to have a fixed T time conversation ( time T is fixed like 5 min or 10 min) with each ...
2answers
2k views

### Find the order of students presentation(logical puzzle)

Four students P, Q, R and S each working under the super vision of one of the four professors A, B, C and D made their final year MBA Project Presentations one by one, one each in the areas of Finance,...
1answer
574 views

### A cube puzzle (Multiple of 6)

If you have a cube, say, $3 \times 3 \times 3$, you know that mathematically it's made of $27$ ($3*3*3$) smaller cubes. Now, just remove one full line of smaller cubes (in this case, 3 smaller cubes). ...
1answer
7k views

### 10 little dwarves [duplicate]

A dwarf-killing giant lines up 10 dwarfs from shortest to tallest. Each dwarf can see all the shortest dwarfs in front of him, but cannot see the dwarfs behind himself. The giant randomly puts a ...
2answers
720 views

### First number, which can not be defined

What is the appropriate answer to this question? What is the first natural number, which can not be defined with less than 15 words? Explanations: 1. Natural means integers greater than 0. ...
1answer
527 views

### Number of true sentences

You are given a sheet of paper with $100$ sentences, in the form of: There are exactly $x$ wrong sentences on this sheet. There is exactly $1$ wrong sentence on this sheet. There are exactly $2$ ...
1answer
663 views

### 3 Switches identification [duplicate]

Picture this. You are in a hallway of a very large office building. Near you are 50 light switches of which 3 are unlabled. These lightswitches are connected to 3 lights in 3 separate rooms. The ...
1answer
564 views

### Could a gold/{second metal} crown the be created that would pass the Archimedes test cost effectively? [closed]

Many people are familiar with the story of Archimedes submerging a crown in water to identify if the volume of the crown was consistent with the volume of the same amount of gold. The test was to see ...
1answer
863 views

### Clock Puzzle problem

Today I came across this puzzle: How many minutes is it until six o'clock if fifty minutes ago it was four times as many minutes past three o'clock? Any help?