BrainDen.com - Brain Teasers

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## Popular Content

Showing content with the highest reputation since 01/21/19 in Posts

1. 2 points

2. 1 point

## Poisonous apples

There are two bowls that you and a challenger must eat from. After flipping a coin you were selected to pick the bowl that each would eat from. In the first bowl there are three out of five poisonous apples. In the second bowl, there are two out of five poisonous apples. Whoever eats from the first bowl must eat two apples at random from the bowl. Whoever eats from the second bowl must eat three random apples from the second bowl. Which bowl should you pick to eat?
3. 1 point

## Triangle

Form a "Triangle" With 10 blocks in its top row, 9 blocks in the next row, etc., until the bottom row has one block. Each row is centered below the row above it. Color the blocks in the top row red, white, or green (or any three colors of your choosing) in any way. Use these two rules to color the remaining rows of the triangle: - If two consecutive blocks in a row have the same color, the block between them in the row below has the same color - If two consecutive blocks in a row have different colors, the block between them in the row below has the third color Tell how you can always predict the color of the bottom block after seeing only the top row (and not constructing the intermediate rows) PROVE your answer.
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5. 1 point

## Crocodile Sophism

Crocodile Sophism - Back to the Paradoxes A slim crocodile living in Nile took a child. Mother begged to give him back. The crocodile could not only talk, he was also a great sophist, and so he stated: "If you guess (Edited: predict the fate = guess correctly), what I will do with him, I will return him. However, if you don't guess his fate I'll eat him." What statement shall the mother make to save her child (what about a vicious circle ...)?
6. 1 point

## Hats on a death row!! One of my favorites puzzles!

Revolt. The king is totally corrupt. The concept of justice is perverted. He doesn't deserve to be king. When everyone is lined up, everybody jump the guards and fight your way out. It is better too die on your feet than live on your knees.
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LEGEND
8. 1 point

## Massive multiplication

n factorial (represented as n!) is the product of all positive integers up to n. So the number you are looking for is 1,000,000! ("one million factorial")
9. 1 point

## What Am I?

The letter Y?
10. 1 point

## Walking, running, driving, waiting

I'll accept it but I was thinking more like ....
11. 1 point

## Walking, running, driving, waiting

With a tip of the hat to @BMAD for his interesting puzzle. For your amusement, here's an interesting spin on this genre: One night you encounter a two-hour traffic delay due to an accident (the tow truck had difficulty clearing the road.) So, for a time interval 13 of two hours you were constrained to travel at 0 mph. You called home and said, sorry dear, but I'll be two hours late getting home. The next night, for some unimaginable reason, you were also constrained to travel part of the way at 0 mph, this time for a distance of one inch. What do you say now when you call home?
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13. 1 point

## The Pebbles

We are in a TV game. We have 8 same looking boxes, each of which has 2 pebbles. Each pebble could be either precious or not precious. We choose a box and the host, without looking inside the box, pulls out a pebble. It comes out to be precious. The TV host then declares that we have exactly 50% chance that the 2nd pebble inside the box is precious, too. If we know that, in the beginning of the game, the count of precious pebbles is no less than the count of not precious pebbles, which of the statements MUST be true? We assume that the TV host knows the pebbles distribution in the boxes - in what amount of boxes the precious pebbles are 0,1 or 2. The TV host, however, doesn't know the kind of pebbles in each specific box, as he himself doesn't differ the boxes from one another. 1. If we swapped the boxes, we would have higher chance of picking up precious pebble next. 2. If we swapped the boxes, we would have same chance of picking up precious pebble next. 3. If we swapped the boxes, we would have lower chance of picking up precious pebble next. 4. In the beggining of the game, there've been exactly 2 boxes with 2 precious pebbles each. 5. In the beginning of the game, half the boxes have had 1 precious and 1 not precious pebble. 6. In the beginning of the game, the precious and not precious pebbles have been equal in count. 7. In the beginning of the game, the amount of boxes with 2 precious pebbles is equal to the amount of boxes with 2 not precious pebbles. 8. The TV host has gone wrong. There's no way that there's 50% chance for 2nd precious pebble in our box, as there is unequal amount of pebbles left in the game. 9. None of the above must be true.
14. 1 point

## Nameless Riddle

Well THAT fell fast!
15. 1 point

## 12 chess pieces

Question about #13, which sounds to me like a conflict. should it read “ nothing is south of the one black rook, which is on the edge”? or should it read “ nothing is south of the white rook that is on the edge” or even “one of the white rooks is on the edge, and has nothing south of it”? for that matter, should it name a different piece than white rook?
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## DUCK

Son, father and grandfather - three only
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18. 1 point

## shuffling algorithm for letters in a word

It looks like you're taking the first letter and essentially rotating it through the different positions while the other letters remain in the same order. I noticed that all the possible permutations begin with two letters that were next to each other in the original sequence (or in the first and last spot). For example, I don't think you can get a sequence starting with AC. So this does not seem to hold up.
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## Good-natured Trump jokes

A joke from the internet yesterday: Trump really delivered when he said he would run the government just like his businesses. It's already shutdown! Don't worry, he still has three years to bankrupt it.
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## 1000 people in a circle

Assuming N people, the last standing (S) is given by: S=2*(N-2^m)+1, where m=floor[ln(N)].
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## I'm not a rebellious missionary

Right on, PG, and glad you like it. This one I think I'll keep in a Sundae Best collection.
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I have just created Homework Help forum. I have also started the first topic to list all members willing to help. Read the rules and feel free to ask questions and help others to find solutions/answers. Enjoy!
23. -1 points

## Atlas

Hi guys, I love riddles so much that I wanted to insert it in game me and my friend are making. The game is 2D RPG roguelike survival game happening in a randomly generated universe. Here is the fun part, one of the random encounters will be the character in a game that will approach the player and ask him a riddle. If a player answers correctly he will be awarded else Riddler will attack the player. (About 10% of NPC encounters in the game will be by riddler). I think that's the cool way to promote riddles and make kids (and grownups) use the brain. Also please write me some riddles and I will insert it in game. Thank you, Josip
24. -1 points

## What Am I?

electricity double letters
25. -1 points

Electricity
26. -1 points

## Hard Riddle.

What cannot move but can travel?
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