Sarah’s Mother
If Sarah’s mother is Barbara, then Barbara is the ??? of Sarah’s mother.
SOLUTION
The answer is NAME.
Category: Brain Teasers
A collection of Math, Chess, Detective, Lateral, Insight, Science, Practical, and Deduction puzzles, carefully curated by Puzzle Prime.
Puzzle Prime is tirelessly looking all around the internet to find the very best puzzles and bring them all to puzzleprime.com.
Policeman and Thief
A town consists of 3 horizontal and 3 vertical roads, separated by 4 square blocks. A policeman and a thief are running along the roads with speeds of 21km/h and 10km/h respectively. Show that the policeman has a strategy ensuring he will eventually see the thief.
Remark: The policeman can see the thief if they are on the same road at some moment. He has no idea about his position at any time.
SOLUTION
A working strategy for the policeman would be to go to the center and to start encompassing the four blocks clock-wise one by one, in a clockwise manner.
Since the policeman is twice as fast as the thief if the thief is in the center of the town at some point, then there exists a moment in which the policeman is in the center, and the thief is not on the boundary, i.e. he gets shot.
Now, assuming the thief never visits the center, his angle with respect to the coordinate system defined by the two middle roads changes continuously. The angle of the policeman with respect to the same coordinate system can be defined to change continuously as well. Since the policeman needs less time to increase his angle with 360 degrees than the thief, there will be a moment when the two have the same angle. However, this implies that the policeman will be able to see the thief and shoot him.
Cork in a Glass
You have a jar filled with water and a glass. If you pour some water into the glass and place a cork in it, the cork will float towards the edges of the glass. What is the easiest way to make the cork float towards the center?
SOLUTION
Since the liquid molecules adhere to the glass molecules on the sides of the glass, the water level there is higher and buoyancy makes the cork float in that direction. If you fill the glass all the way to the edge, then the water surface will be convex and the cork will float towards the center.
Lucky Day
Scientists have discovered that on one particular date in the year, there is
SOLUTION
February 29 – it happens only once every four years.
Picture from Russia
Look at the picture below and answer the following questions:
- What time of the day is it
? Is it early spring or a late fall?- Is the river navigable?
- Which direction does the river flow? (North, East, South or West?)
- Is the river deep or shallow at the side where the boat is?
- Is there a bridge across the river nearby?
- How far is the railroad from here?
- Do the birds fly North or South?
SOLUTION
2. People are sowing the crops, so it is early spring.
8. Since it is spring, birds are flying North.
1. Since birds are flying North, the shadows are pointing East, and therefore it is morning.
4. Judging by the water around the buoy, the river is flowing South.
3. Since there is a buoy, the river must be navigable.
5. The fishing line is long, so the river must be deep.
6. There would not be a ferry if there was a bridge nearby.
7. The guy on the left looks like a railroad worker, so probably the railroad is nearby.
Knocked Off Piece
The following position occurs in a real game, right after one of the pieces gets knocked off the board. What was the piece?
SOLUTION
It was a black knight. First, notice that the black pawns have moved 14 times diagonally and thus they have taken 14 pieces. Therefore the knocked off piece is black. Since it is impossible for both kings to be checked at the same time, the missing piece was positioned on a2. It couldn’t be a queen or a rook, because the white king would be checked both by it and the pawn on b3, which is impossible. Therefore the missing piece is either the black white-squared bishop or the black knight. However, the pawns on b7 and d7 haven’t been moved the entire game and then the black white-squared bishop hasn’t either. Thus we conclude that the knocked off piece is a black knight.
Tetris Puzzle
As a birthday present last year, I received some fridge magnets. They didn’t come as a puzzle, so I don’t know if they have a solution, but I made a puzzle out of them anyway. The magnets are tetrominoes. There are 7 of each shape. Is it possible to arrange them into a 7×28 rectangle so that they are all used and all inside the rectangle? The closest I have managed is this:
SOLUTION
No, it is impossible. Imagine you are placing the tetrominoes on a 7×28 chess board. All of them, except for the T-shaped ones cover exactly 2 black and 2 white cells. Each of the T-shaped tetrominos covers either 2 more black cells than white cells or 2 more white cells than black cells. Since there are 7 of them, combined they will cover either more black cells than white cells or more white cells than black cells. Therefore all pieces on the picture can not cover perfectly a rectangle, which contains an equal number of black and white cells.
Source:
Out of Place
Which of the numbers below is out of place and why?
1011, 2223, 3940, 5646, 8910
SOLUTION
Every number except 5646 can be split into a sequence of consecutive numbers: 1011~10-11, 2223~22-23, 3940~39-40, 8910~8-9-10.
Two Games at Once
The Devil offers you a deal – you have to play two games of chess simultaneously against the two best GrandMasters in the world, one with black pieces and one with white pieces. If you win at least 1 point from the two games, you will get whatever your heart desires, if you don’t – you will go straight to Hell. Would you accept the challenge?
SOLUTION
Accept the challenge. You can easily get 1 point by just repeating the moves of your opponents. For example, if the white GrandMaster plays e4, then you play e4 against the black GrandMaster. If the back GrandMaster plays e5, then you play e5 against the white GrandMaster and so on.
Magic Liquid
You buy a bottle with a letter from the merchant, the merchant tells you that when you drink the liquid in the bottle it grants you eternal life, he supposedly deciphered this from the letter.
After you get home you decide to study the letter if it really says what the merchant told you, can you figure out if the bottle really grants eternal life?
You come to a fork in the road.
To the left is an empty well made from stone.
On the right is a pirate’s buried treasure.
Ahead you only see a tall straight tree.
The night is dark with only a dying moon in the sky.
Source: Puzzling StackExchange
SOLUTION
The objects described in the last paragraph have the following shapes:
fork in the road = T
empty well = O
buried treasure = X
straight tree = I
dying moon = C
The 5 letters form the word “TOXIC”, which suggests you shouldn’t drink from the bottle.
