# 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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### Humphrey meets Laureen in town

Laureen is talking with Humphrey: "if the weather is good on Sunday I will go to the horse races. I will also bring my friend Sam with me, if he feels ok". on Sunday afternoon Humphrey meets Laureen ...
5k views

### Is this chromatic puzzle always solvable?

I've created a new puzzle from an Alexey Nigin's idea. It consists of a 8x8 board where each square is randomly assigned one of three colors. A movement is defined by picking any two orthogonal ...
310 views

### Nothing is impossible

Here's a little logic-puzzle that I've been thinking about for years and I wanted to hear you oppinion: If nothing was impossible, wouldn't it be impossible to find something that is impossible?
114 views

### About the 100 blue eyes problem [duplicate]

I thought I understood your answer and liked it, but just read a different explanation at http://thesilentknight.info/2016/flawed-logic-blue-spot-problem/ that suggests that the 100 people would all ...
4k views

### Statements that the deities True and False cannot say

You over exert yourself working on logic puzzles and die of exhaustion. You are awoken by the omniscient deities True and False. True only speaks true statements and False only speaks false statements....
2k views

This is an alphametic - Each of the alphabets in the below represents a unique digit in base 10 such that the following representation holds true. ...
254 views

### Amazing sudoku who can find hot numbers

Sudoku X Place the numbers 1-6 once in every row, column, diagonal, and 3x2 block. The diagonals form an X and are highlighted. Puzzle Text of puzzle ----------------- | . . . | 5 . . | | . . . | ...
490 views

### The three girls [duplicate]

A man gets to know his neighbor, and he learns that she has 3 girls. Intrigued, he asks for their age. The lady, who doesn't want to give him this information straight away, has him to take a guess. ...
3k views

### What Imprisonment sentence will immortal citizen soldier Guilt receive?

On planet Immortal, everyone lives forever but essential resources (including food and supplies) on the planet are limited. Ultimatopian raiding swords are the most effective weapon available to loot ...
4k views

### Color elimination puzzle

You have a 5x5 board with on each cell a light that can be red, green or blue. Next to each row and each column there is a button that when pressed makes all red lights in that row/column green, all ...
554 views

### The Drouble with Doorples

You are the first officer aboard the Starship Enterpuzz, and moments after your captain departs for his week-long vacation, you discover that your ship is infested with tiny creatures called doorples. ...
1k views

### Puzzle to find one good person [duplicate]

There are 15 people who may lie or say the truth(bad people) and 16 people who will always say the truth(good) . Suppose A- bad person , B-good person and C-bad person, when asked about A, B will say ...
348 views

487 views

### Correct way to add 22 to 4 to get 9999

Inspired by four other puzzles, how could it be possible that adding 22 to 4 gives 9999? What is the correct way to do it? As with all of the other puzzles, consider these numbers in base 10.
419 views

### The truth and lie mess

There are two persons with special traits such that : One speaks only lies and no truth on Monday, Tuesday and Wednesday and all truth rest of the week. The other speaks only lies and no truth on ...