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- Bielefeld
- tarnheld
This is a place for training that muscle between your ears! Here you can post puzzles, riddles and brain teasers, try to solve them and discuss your quandaries and all things puzzling.
If you want to post a puzzle for others to solve please follow these guidelines:
When giving away hints or answers to any puzzles in this thread, plase use the Insert...Spoiler feature to hide it and not spoil the fun of others trying to solve it. Use the Puzzle Title as Spoiler Title and add "hint" or "solution".
I'll try to keep a record of all puzzles and hints and answers posted so far in post #1. Here is my preliminary system of rating riddling and solving success: each riddler gets a point for each day his puzzle can't be solved, with a capping of points to be determied. Each solver gets a point for solving a puzzle -- barring obvious rephrasing of earlier answers. Lets see if this results in a fair rating system to determine a leaderboard of puzzle solvers and riddle posters.
Happy Puzzling!
If you want to post a puzzle for others to solve please follow these guidelines:
- You should give a short title to your puzzle, like The SuperHard Riddle, to distinuish it from others and for easy reference.
- You should have an answer to the puzzle. (No unsolved problems please)
- The possible anwer(s) should be derivable from the description of the puzzle alone or combining publicly available information and should not involve personal secrets. (Like "What is currently under my pillow?")
- Keep in mind that most puzzles and brain teasers are easily googlable: try to change the wording or invent a different story altogether.
- You may provide hints and after a sufficient time with no progress you can post the answer but please use the Spoiler feature always when giving away hints or the final answer.
- You should refrain from commenting every solution as it is posted, better wait a fair amount of time and post general hints not targeted to a particular solution approach
When giving away hints or answers to any puzzles in this thread, plase use the Insert...Spoiler feature to hide it and not spoil the fun of others trying to solve it. Use the Puzzle Title as Spoiler Title and add "hint" or "solution".
I'll try to keep a record of all puzzles and hints and answers posted so far in post #1. Here is my preliminary system of rating riddling and solving success: each riddler gets a point for each day his puzzle can't be solved, with a capping of points to be determied. Each solver gets a point for solving a puzzle -- barring obvious rephrasing of earlier answers. Lets see if this results in a fair rating system to determine a leaderboard of puzzle solvers and riddle posters.
Puzzles
Can you put ten moles into eight holes, so that each is in one and only one hole?
Clarification: a hole has only room for one.
Clarification: a hole has only room for one.
The young craftsman is in deep thought: he has been assigned to link the five pieces of chain to a single chain. If you count the opening of a chain link and the closing of a chain link as single operations his foreman told him that it is done in eight operations. Can he do better?
Clarification: The opening of a link counts as one operation, the closing of a link is a spearate operation, opening and closing of a link are therefore two operations. A chain has each link attached to not more than two other links.
Clarification: The opening of a link counts as one operation, the closing of a link is a spearate operation, opening and closing of a link are therefore two operations. A chain has each link attached to not more than two other links.
Somewhere in the east there is a monastery on a square shaped property with an area of a square mile. Each day at dusk four monks go to the lookouts at the edges of the fence surrounding the monastery to guard the property. Each monk looks along the side of the fence to another monk, no monk is looked at by more than one monk. At night the bell of the church at the center of the monastery tolls and it's time to change shifts. It is so dark that each monk sees only the lantern of the other monk along the fence he is looking at. So they all start to go towards the lantern of the other monk they see at a speed of two miles an hour.
- Will they ever meet again and where will that be?
- What distance have they traveled?
- What time did the trip take?
Code:
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M<---MYou are moving into your new house with your new spouse after your marriage in Vegas (you don't remember much about this part of the story...). Going around the place you notice three switches and remember that the estate agent told you that one of them switches a single light fixture in the basement and the others do nothing (the agent said it would be an opportunity to put your own stamp on...). You ask your spouse to go downstairs and help you find out which switch is the right one, but turning around you can only see a moving shadow and a yell from the distance: "Honey, you know you have to only go down once to find the switch... I'm off to the pool!"
So how can you find the right switch by going downstairs to the basement only once?
So how can you find the right switch by going downstairs to the basement only once?
I propose to play a game of 66 coins of various denominations. I will arrange these 66 coins in one row on the table in an order of my liking. We then take turns to take one of the coins from either end of the row until they are all gone, with you beginning to take the first coin. The one of us with the highest total value of their coins will win them all, if we have the same total value at the end you win. Can you win this game?
A group of people from the Privacy and Equality Party go on a drinking bout. At the end when it is time to pay they have a special way to split the bill. They calculate the average value of their montly incomes and determine the part they have to pay based on the proportion of their income to the average of the group. So if Jim earns twice as much as the average of a group of eight persons he has to pay a part twice as much as the average part of 1/8, i.e. 1/4 of the bill. But to live up to their privacy promise they have found a way to determine the average value of their incomes without any person in the group having to disclose their individual income to other persons and only by communicating with persons in the group. How could they have done that?
You find a box with fuses (lengths of string to be used for timing explosives) and the instructions on the box say that they each burn for exactly one minute, but not uniformly along their length, i.e. they are not half as long as they were when you let them burn for 30 seconds for example. There are two fuses left in the box. Can you measure 45 seconds using them?
You have two pyramids, one with a square base and one with a triangular face, both having all edges of length one. You glue one face of the triangular pyramid on a triangular face of the other pyramid. How many faces does the resulting solid have?
In days of yore there was a country that was inhabited by thiefs. One of them wanted to quit stealing and had the idea to start a parcel delivery service. But all employees he could find were tempted to steal the contents if not properly secured, so his company seemed to be set to fail right from the start. As everyone in this country needed locks to secure everything he could assume that every customer had many padlocks available to secure the goods to be delivered themselves. But of course the key to each lock was unique so at first it seemed like the receivers weren't able to open the padlocked parcels. But he found a way to make the business work and became a wealthy man. How does delivery work with his service?
8 pieces of paper have been used to create the image below. All pieces are of the same size (A).
In which order have they been placed down?
In which order have they been placed down?
You sit in a imensely boring presentation of your boss about the financal situation of the company. After not so much time has passed your mind starts to wander and you start to doodle away on your sheet of paper, some lines here, some lines there and all of a sudden your sheet ends up like this:
In horror you realize that both rectangles labeled A are the same size, and B and C too. That leaves 4 square units in the left upper part but only 3 in the lower right, and the triangles next to the diagonal of same size. So the upper left part is one unit square bigger than the lower right part! Did you just destroy math? What is going one here?
In horror you realize that both rectangles labeled A are the same size, and B and C too. That leaves 4 square units in the left upper part but only 3 in the lower right, and the triangles next to the diagonal of same size. So the upper left part is one unit square bigger than the lower right part! Did you just destroy math? What is going one here?
After you have quickly erased the devilish doodle but still ages away from being finished with watching the presentation you want to find solace in honeycombs and try to draw regular hexagons. But they won't come out as regular hexagons if the corner points are put on the intersections of the square unit grid:
Either the sides are not all equal, or they don't lie all on the same circle. So can you find a way to put the corners of a regular hexagon on the corners of a square grid, or is it impossible?
Either the sides are not all equal, or they don't lie all on the same circle. So can you find a way to put the corners of a regular hexagon on the corners of a square grid, or is it impossible?
On most days, Camile and Melissa (sisters) walk a short distance towards the city (for the exercise) down a narrow road in front of their house as they wait for the bus (which has doors on both sides) to come by and pick them up for the trip into the city where they work.
On one occasion, as they are walking down the road, they spot two cars on the side of the road. On the left side of the road is a Chevy Camaro which is sitting just over 40 meters from the road. On the right side of the road is a Ford Mustang which is sitting just over 41 meters from the road. The two sisters are huge car enthusiasts, so Camile walks over to the Chevy Camaro and Melissa walks over to the Ford Mustang for a look.
Suddenly, they look up and see that their bus is coming along down the road. When they look up, the bus is 70 meters further back up the road from where the sisters left the road to view the two cars. The bus is traveling slowly because the road is only a wide as the bus, and because it normally expects to pick up the two sisters, but it won't stop since the bus driver doesn't like to stop unless there is someone actually waiting on the road.
The sisters immediately begin to run towards the bus at an angle towards where they expect to meet/catch the bus once they reach the road. Since the bus is traveling slowly towards the city, the two sisters are able to run at half the speed that the bus is traveling.
Can the sisters catch the bus?
How far will the bus have traveled from where they first noticed it?
On one occasion, as they are walking down the road, they spot two cars on the side of the road. On the left side of the road is a Chevy Camaro which is sitting just over 40 meters from the road. On the right side of the road is a Ford Mustang which is sitting just over 41 meters from the road. The two sisters are huge car enthusiasts, so Camile walks over to the Chevy Camaro and Melissa walks over to the Ford Mustang for a look.
Suddenly, they look up and see that their bus is coming along down the road. When they look up, the bus is 70 meters further back up the road from where the sisters left the road to view the two cars. The bus is traveling slowly because the road is only a wide as the bus, and because it normally expects to pick up the two sisters, but it won't stop since the bus driver doesn't like to stop unless there is someone actually waiting on the road.
The sisters immediately begin to run towards the bus at an angle towards where they expect to meet/catch the bus once they reach the road. Since the bus is traveling slowly towards the city, the two sisters are able to run at half the speed that the bus is traveling.
Can the sisters catch the bus?
How far will the bus have traveled from where they first noticed it?
The common sudoku solver is delighted when one puzzle is finally solved and all numbers are entered and the sudoku conditions are met. But in fact not just one is solved: imagine rotating the sudoku grid by 90 degree and you have another assignment of numbers for all grid cells, that makes two sudokus. Are there more ways to rearrange a sudoku? When you solve one sudoku instance, just how many sudokus have you solved actually?
In a small county not far away the 65 citizens revolted and disempowered the king, now each citizen including the king gets an hourly wage of 1 dollar. The king can no longer vote himself, but he retained the power to suggest wage changes. The wage of each citizen must be a whole number of dollars, and the sum of all wages must be the number of citizens.
The suggestions are voted on and carried if there are more "yes" votes than "no" votes. Each citizen can be counted on to vote "yes" if his wage increases, "no" if it decreases and not to bother voting if it doesn't change at all.
The king is of course selfish and clever. What is the maximum salary he can get for himself and how long does it take to get it?
The suggestions are voted on and carried if there are more "yes" votes than "no" votes. Each citizen can be counted on to vote "yes" if his wage increases, "no" if it decreases and not to bother voting if it doesn't change at all.
The king is of course selfish and clever. What is the maximum salary he can get for himself and how long does it take to get it?
Fill in the following cross-number square:
_ _ _ _ _
_ _ x x _
_ _ _ _ x
x _ _ _ _
_ x _ x _
All horizontal and vertical numbers must be either squares or cubes of an integer unless the integer is the squareroot of 121.
This shouldn't be too hard.
I have found two answers so far.....
Good luck!
_ _ _ _ _
_ _ x x _
_ _ _ _ x
x _ _ _ _
_ x _ x _
All horizontal and vertical numbers must be either squares or cubes of an integer unless the integer is the squareroot of 121.
This shouldn't be too hard.
I have found two answers so far.....
Good luck!
On your quest for the Holy Grail you encounter the Knights who say Ni!. They refuse to allow passage through their woods unless you bring them a shrubbery, one that looks nice, is not too expensive and is arranged in the form of the light gray part of this diagram:
After you harrassed the local villagers to fullfill their wish, you find them no longer being the Knights of Ni, but the Knights who say "Ekke Ekke Ekke Ekke Ptang Zoo Boing!". Also they now demand a rectangular shubbery. Can you fullfill their wish by cutting the original shrubbery into pieces (using a herring provided by the Knights who until recently said Ni!) and rearranging them into a rectangle and not wasting any piece of it?
After you harrassed the local villagers to fullfill their wish, you find them no longer being the Knights of Ni, but the Knights who say "Ekke Ekke Ekke Ekke Ptang Zoo Boing!". Also they now demand a rectangular shubbery. Can you fullfill their wish by cutting the original shrubbery into pieces (using a herring provided by the Knights who until recently said Ni!) and rearranging them into a rectangle and not wasting any piece of it?
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Happy Puzzling!
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Remember, eight steps is the number to beat.
If you have any questions this is the place to ask!
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So here it is (not to scale):
There's a tension between being precise and giving away too much hints about how to approach the problem. But it's a lot of fun transforming these stories.
Can i persuade you to post a nice riddle yourself, Mr. Holmes? 
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