Category Archives: Inductive reasoning

Pattern codes – graphs

Inductive reasoning

1) Graphs
What code goes to the question mark?
Pattern code graph exercise

You can check your solution here


A new puzzle is published every friday. The solution is generally published one week later. I welcome your reactions on these puzzles: are they too easy, too difficult, are there any multiple solutions? How long did you need to solve it?

Letter square

Alphabet, Inductive reasoning

Conside the following square with letters.
Square alphabet

What number should go into the cell with the question mark?

Please try to solve the puzzles on your own. You are welcome to remark on the puzzles, and I love it when you comment variations, state wether they are too easy or too difficult, or simply your solution times. Please do not state the soultions – it spoils the fun for others. I usually make the solution available after one or two weeks through a link, which allows readers to check the solution without the temptation to scroll down a few lines before having a go at it themselves.

When you have solved this puzzle, you can check your solution here

You can find more puzzles like this one in our upcoming e-book on Logic Puzzles.

Color grid (1)

Inductive reasoning,

What number goes into the cell with the question mark?

1) Color grid*
color grid 2014-02-12 nr 1 exercise

You can check your solution at here

Please try to solve the puzzles on your own: your self confidence will grow. You are welcome to remark on the puzzles, and I love it when you comment variations, state wether they are too easy or too difficult, or simply your solution times. Please do not state the soultions – it spoils the fun for others. I usually make the solution available after one or two weeks through a link, which allows readers to check the solution without the temptation to scroll down a few lines before having a go at it themselves.

You can find more puzzles of this type in one of our free or paid upcoming e-books on Logic puzzles.

Eleusis

Inductive reasoning, Playing cards,

Yes, I know my slogan is “just puzzles”. So I shouldn’t be writing about games. Having said that, let me first explain the game of Eleusis before proceeding to the puzzles.

The game of Eleusis was invented by Robert Abbott in 1956, and is totally different from such games as bridge or poker. Eleusis is played with a standard card deck of 52 cards. One player thinks of a secret rule and preferably writes this down. He playes two cards which obey the secret rule. All other players receive a number of cards, for example each player receives 5 cards.

The two cards are the beginning of a line of cards. The other players now take turns in playing a card to the end of the line. When a player plays a card, the Rule Inventor indicates whether the card obeys the rule. If it does, it is added to the end of the line. If it does not, the card is placed below the line and the player draws two extra cards from the deck. In both cases, the turn passes to the next player. The player who first gets rid of all his cards wins.

Example:
Eleusis - demo

In this sample game, the Rule Inventor played Ace of diamnonds and 2 of Hearts. The first player played 3 of diamonds, which the Rule inventor turned down. The second player played Jack of diamonds, which turned out to be also incorrect. The 3rd player tried 3 of clubs, which the Rule Inventor added to the top row. The next two cards played were a 9 of hearts and a 10 of diamonds, which the Rule Inventor both declared to be wrong. The last card played was the Ace of spades.

Now here is a rule to find out.
1) Rule 1*
Eleusis - problem 1 - exercise

In your hand you have:
Eleusis - problem 1 - hand

Which of them do you play? And why?

2) Rule 2**
Eleusis - problem 2 - exercise

In your hand you have:
Eleusis - problem 2 - hand

Which of them do you play? And why?

In the explantion of the game above I omitted 2 complications:
– if the player thinks he can not play a valid card, he may claim this and exchange his hand. If he is right, he exchanges his hand for a hand with one card less from the deck. If he is wrong, the RuleInventor plays a correct card and the player draws two cards from the deck.
– if a player thinks he knows the secret rule, he may declare himself prophet. The prophet now first judges all cards played, before the Rule Inventor. If he keeps his job till the end of the game, he wins the game instead of the player who first gets rid of all his cards.

Though I am out of touch with him now, I have very good memories of my correspondence with him about two decades ago, and he is a very kind man.

As usual, you are welcome to report your solution times and comment on the solution, but please do not give away the answer – that may spoil the fun for others. I will publish the solution in one or two weeks after posting the puzzle.

You can check your solution here and

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New puzzles are published every Friday, at which time also the solution to the previous weeks puzzle is published.

You can expect more Eleusis based puzzles in one of the upcoming free e-books.

Incidentally, this is the 100th post on this blog. The game Eleusis is an old favourite of mine, and thus a worthy subject of this celebration.

Yes/No

Inductive reasoning

There is a well known family game where one person takes an object in mind, and the rest of the company may ask yes/no questions and have to guess what it is.

Example:
A: OK, I’ve got something in mind
B: Is it something I can touch?
A: No.
B: So it is something abstract?
A: Hm, no
C: Is it something I can hear?
A: No
D: Is it something I can see?
A: Yes!
B: Is it inside the house?
A: No
C: Can it always be seen?
A: No
D: Just on certain days?
A: Question not clear, but probably no.
and so on.
(btw, if you want to know what A has in mind, you can ask me yes/no questions at the bottom of this page)

This kind of game consists of a series of puzzles. There is a variant, in which baffling stories are presented, and people may ask yes/no questions to explain the situation.

Exif_JPEG_PICTUREWell known examples are:
A) A man goes down with the elevator everyday. When he returns from work, he goes up half way, and takes the stairs. Unless it rains, then he goes up all the way.
B) A man is lying in a meadow. He is dead. Besides him there is a white package.
c) A man walks into a saloon. The bartender pulls his gun at the man. The man says: “thank you” and leaves the saloon.
I first heard these puzzles when I was a teenager, and you can find the solutions on several places on the web.

For those who are interested in this kind of puzzle, Paulo Sloane runs a forum with this kind of puzles at www.lateralpuzzles.com. He is also the author of the book “Lateral thinking puzzlers”.