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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5
votes
2answers
38 views

Akari: Another Light

Rules (taken from Nikoli): Place light bulbs (circles) according to the following rules. Light bulbs may be placed in any of the white squares, the number in the square shows how many light ...
9
votes
1answer
181 views

Akari: The Light

Rules (taken from Nikoli): Place light bulbs (circles) according to the following rules. Light bulbs may be placed in any of the white squares, the number in the square shows how many light ...
9
votes
3answers
391 views

Pieces of paper without consecutivity condition

TL;DR: like this puzzle but with an arbitrary number of papers and without the condition that the papers chosen must be consecutive. You are given $n$ pieces of paper, and you write down $n$ distinct ...
13
votes
3answers
1k views

A mini game with 15 pieces of paper

You are given $15$ pieces of paper, you are asked to write down any distinct integer numbers on them as you wish. Then these pieces of paper will be turned back, mixed and put on the table in a ...
11
votes
6answers
21k views

Mensa Norway last 3 questions

I had no problems with solving first 32 questions from http://test.mensa.no but the last 3 questions are totally bugging me out even knowing the answers. Could anyone help me getting the logic behind ...
2
votes
1answer
94 views

Setka Puzzle - Complete grid using clues and sudoku-style logic; Tom Hanks

Theme: Tom Hanks This is a Setka puzzle; you can find more (along with a more detailed explanation of the rules) at our website, linked from our profile. How to play Setka, the short version: ...
5
votes
1answer
293 views

The Weird cipher password?

During your search to the ' great hidden computer virus ' , you realized that you are just a password from accessing it. Frantically , you searched for a clue that might help you . At last you ...
3
votes
2answers
128 views

Great POTW Bake-Off

Pepper, Belle, Emerson, and Ralphie have just competed in POTW’s Annual Bake-Off. Pepper, Belle, Emerson, and Ralphie each came in first, second, third, or fourth in the competition. There were no ...
31
votes
1answer
3k views

MASTERING Sudoku

Fill the grid with letters M, A, S, T, E, R, I, N and G. Standard Sudoku rules apply. Additionally, the words on the right-hand side must appear in the given orientation (across/down). Each word ...
-2
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0answers
52 views

what are charachteristics of deductive thinking? [closed]

I have heard people talk about deductive thinking and that it is different from inductive thinking but what are the characteristics of deductive thinking?
4
votes
2answers
125 views

How can I make a valid conclusion about a set of statements which are in tandem?

The problem is as follows: If there are no government subsidies for agriculture, then there are government controls on agriculture. If there are government controls on agriculture, then there ...
1
vote
0answers
147 views

Math tapestry puzzle #3

Continuation from Math tapestry puzzle #2 Now things are heating up, it looks like this is slowly becoming bigger. I saw my friend Anna working on her tapestry. She asks me, "Do you like it?" ...
1
vote
1answer
75 views

How can I find which sport/hobby corresponds to which friend when a set of given clues is provided?

Marina, Mike, Roger, Phillip and Justin has each only one hobby from the following list: motocross, badminton, swimming, athletics and karate, but not necessarily in that order. It is known that: ...
31
votes
1answer
1k views

This cipher needs a name!

This puzzle is a spin-off from the 'This new puzzle type needs a name' series. I have devised a new cipher and used it to encode its own name. I need you to tell me: What is its name? This puzzle ...
0
votes
1answer
85 views

Math tapestry puzzle #2

This continues from Math tapestry puzzle #1. Find the rules there. Continuing on from that, I saw my friend Jason come outside. We had a conversation about the things that are here. Suddenly he says: ...
3
votes
2answers
115 views

How can I find which person belongs to a specific occupation when the clues involve degree of friendship or acquaintance?

The riddle is as follows: Brenda, Lara, Mie and Nancy have each one profession. These professions are, baker, graphics designer, photographer and cosmetologist. But not necessarily in that ...
3
votes
1answer
127 views

Fork in the road problem - with a single person

You walk to a fork from where two roads come out - one leading to a post office and the other to a university. You want to go to the university, but do not know which road would lead you to it. A ...
60
votes
14answers
19k views

Are there eighteen or twenty bars in my castle?

Two friends, Mark and Rose, are very famous logicians; they are so clever that they can deduce any logic connection possible in a matter of minutes even from the most vague situation. Unfortunately, ...
6
votes
3answers
209 views

A Game of Dice and Logic II

Part 1, same game rules, slightly different cards This question is broken - my program for proper analysis failed in some catastrophic way, and the question does not work as planned. The intended ...
15
votes
5answers
1k views

A Game of Dice and Logic

A friend and I are playing a cooperative game. He has two D7 dice and 5 cards in front of him. They read; ...
6
votes
1answer
125 views

Puzzle - Snow Day Event

Daisy, Delilah, Donny, and Duke have each decided to participate in the snowperson building event. In decorating their snowperson, each of them has chosen a different colour of the scarf from purple, ...
2
votes
1answer
151 views

Math tapestry puzzle #1

I went outside. I saw several math tapestries. Apparently they mean something. What goes in spot NN? I know from my friend that... Two adjacent numbers always have the same sum. The 4 numbers in each ...
8
votes
1answer
683 views

Who attempted to betray the Boston King?

The Castle of Weshire recently declared war on the Castle of Boston. The two armies soon met, the Boston King and Weshire King giving out orders from behind their lines of soldiers, surround by their ...
12
votes
2answers
2k views

It's my sister's birthday

I'd ordered her a cake, but when I got to the bakery to pick it up, the cake decorator had transposed the digits of her age. "She'll thank you for the compliment," I said, "but her age is a prime ...
7
votes
1answer
138 views

Guessing the coin flips [duplicate]

Two prisoners, Alice and Bob, are captured by a dragon and placed in separate, isolated cells. The dragon then flips an infinite number of fair coins, and tells the outcomes of odd throws to Alice and ...
3
votes
0answers
91 views

Splitting a Grid in 4 Equal Portions [closed]

I was wondering if someone could provide a solution to this. Instructions are provided. Thank you.
6
votes
2answers
361 views

Smullyan Logic Puzzle about Nelson Goodman Principle - Knights and Knaves

In Smullyan's "Logical Labyrinths" there is the following problem 1.11: ...
7
votes
1answer
182 views

Two persons and one question “Is the shaman honest”. Which one of them is the shaman?

An anthropologist arrived to the shaman's den where there were two persons, one with a green hat and one with a blue hat. One of the shaman's students had said that there was a Star Predictor with the ...
6
votes
2answers
352 views

Puzzle - Counting Lights, Not Sheep

Some nights it is difficult to get to sleep. On one such night, John counted the number of LEDs (Light-Emitting Diodes) on his clock radio that was on to make each individual time from 10:00 PM to 12:...
1
vote
1answer
85 views

Setka - Complete grid using clues and sudoku-style logic; Theme - Greenwich Village Resident

This is a Setka puzzle; you can find more (along with a more detailed explanation of the rules) at our website, linked from our profile. Theme: Greenwich Village Resident How to play Setka, the ...
5
votes
3answers
9k views

Finding Day Puzzles

When the day after tomorrow becomes yesterday, the day which would then be today will be as far from Sunday as the day which is yesterday when it's two days after that day's tomorrow. What day of the ...
38
votes
13answers
8k views

6 prisoners, 2 colors, one mute

Just like the classic 4 prisoners hats riddle, here we have 6 prisoners buried to their necks in the ground. They can only look straight ahead so that A only sees B, C, D, E while B sees C, D, E, and ...
6
votes
1answer
138 views

Cryptic Setka - Complete grid using clues and sudoku-style logic

This is a Setka puzzle; you can find more (along with a more detailed explanation of the rules) at our website, linked from this user's profile. How to play Setka, the short version: Answer each ...
15
votes
4answers
8k views

The Harry Potter Potions Riddle

A simple riddle from the first Harry Potter book. You are in a room with seven potions. There is a doorway ahead and a doorway behind, both engulfed in flames. Which potion will allow you to move ...
7
votes
1answer
152 views

Montague Island Mysteries Logic-Grid Puzzles

I'm working through the logic-grid puzzles in the book called "Montague Island Mysteries" by R. Wayne Schmittberger. The particular puzzle I'm on is Puzzle 5.3 where breakfast guests choose food ...
8
votes
1answer
226 views

Can you solve this football league table problem?

Each team (A,B,C,D,E,F) plays each other once (on a neutral ground). Maximum number of goals scorable is 4. A team gets $3$ points for a win, $1$ point for a draw and $0$ points for a loss. At the ...
12
votes
3answers
967 views

The Troll, the dwarves and the gloves

A group of $N$ dwarves are caught by an evil Troll. As usual the Troll gives the dwarves a chance to escape if they solve a puzzle he created just for the occasion. Tomorrow morning each dwarf will ...
-1
votes
1answer
74 views

Figure out the next two numbers in this sequence [duplicate]

1,11,21,1211,111221,312211,13112221,1113213211,....? Find the next two numbers in the sequence This question appeared in my math competition and I managed to solve it, and I will give a hint if ...
2
votes
2answers
209 views

Guess the numbers

One day Bob and Alice walk around they were having the following conversation: Bob: Alice go ahead and pick any random number. Alice: Okay, I have one. Bob: Alice multiply the random ...
14
votes
2answers
365 views

Next date with distinct digits

The date today is 7th June 2019, or 07/06/2019 (using the English DD/MM/YYYY ordering). When is the next date that when written in this way has all eight digits different?
5
votes
2answers
151 views

Is “meta”-logic valid for solving puzzles? [duplicate]

I think this question is best explained with a demonstration. In this case I'm playing a Range puzzle, but this kind of concept seems to work with other puzzle types too. Of interest here are the two ...
14
votes
3answers
1k views

A King's Hamiltonian Tours

a) Place the numbers 1 to 25 in the cells of a 5 x 5 board in such a way that consecutive numbers occur in adjacent cells either vertically, horizontally, or diagonally, and so do cells with numbers 1 ...
17
votes
4answers
2k views

Paint 21 Squares of a 7×7 Board Without Forming a Rectangle

Got a nice puzzle from my friend, when he was competing in IWYMIC/IMC 2011. Paint $21$ of the $49$ squares of a $7 \times 7$ board so that no four painted squares form the four corners of a rectangle....
5
votes
1answer
173 views

Just Another Sudoku for PSE

Crafted with love for PSE, <3
3
votes
2answers
147 views

The Mixed-Up Label [duplicate]

Mrs. Hudson had a rather large number of her extended family over for tea, and during this time a particularly mischievous great-nephew took the opportunity to wreak havoc in the kitchen. Seeing that ...
21
votes
1answer
3k views

Logic puzzle: Driving around the United States

For Super Bowl Sunday, here's a super-sized logic puzzle! This was a practice puzzle for a hunt I participated in a few years ago. There are ten delivery drivers driving around the United States of ...
10
votes
1answer
252 views

Double Chocolate: Happy Valentine's Day!

Hikouki (@flight_float) over on Twitter issued a challenge to make a Double Chocolate logic puzzle with a fixed grid pattern, and lots of logic puzzle makers responded to that challenge! Here's my ...
33
votes
7answers
6k views

Living next door to Alice

Bob and Charlie live in a small village with 99 houses, numbered from 1 to 99. One day they meet Alice, a person who has recently moved to this village. Bob asks her if her house number is a square ...
17
votes
7answers
3k views

When was Alice Born?

This is inspired by the following recent question: Living next door to Alice Having failed to figure out where Alice lives, Bob and Charlie endeavour to determine the month in which Alice was born. ...
17
votes
1answer
583 views

On The Subject of Blind Alleys

(This is part of a series of puzzles written for Timwi for a Secret Santa puzzle exchange, themed around various custom modules for the game Keep Talking and Nobody Explodes. No KTaNE knowledge is ...

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