中国在联合国人权理事会举办“共同构建人...
百度 中国政府于5月改变了对人民币市场汇价的确定规则，人民币汇率终于开始走稳。
A mathematical puzzle whose essential nature involves randomness. Use with [mathematics]
455 questions
11
votes
2
answers
1k
views
A disk and a triangle: What is the probability of intersection?
An equilateral triangle has one vertex at the centre of a disk.
One side of the triangle lies completely outside the disk and is colored green.
A red line is drawn through two independent, uniformly ...
- 2,942
-2
votes
0
answers
182
views
How did Alice cheat against Bob at poker?
?? Warning ?? You might not like this puzzle if you don't know Texas Holdem Poker rules (or if you hate this game!)
Bob and Alice are playing Texas Holdem Poker. They have a lot of fun but Alice a ...
- 7,888
5
votes
1
answer
336
views
Prime and Alphabet Draws - Puzzling Stack Exchange
The first prime numbers are: 2, 3, 5, 7, 11, 13, 17, 19, 23, 31, ...
At step one, you will draw 2 letters complety at random among the 26 letters of the alphabet.
You might for instance draw: "A&...
- 7,888
44
votes
1
answer
2k
views
Here is the probability, but what was the question?
While solving a problem about flipping coins, Blaise divided SPINED by STIPEND and got a probability of about 17.6%.
What problem was Blaise trying to solve?
(As usual in cryptarithms, the letters S, ...
- 2,331
17
votes
11
answers
2k
views
Roulette Paradox
I have not seen the following simple paradox anywhere. Maybe most people are so smart that for them it isn't a paradox at all, but I think it is worth identifying.
Is it a "puzzle"? Well, is ...
- 4,846
5
votes
2
answers
559
views
Fermat and Pascal play a game
Fermat and Pascal is playing a game with no tie. The final prize is €10000.
A player who won 7 games first takes a prize.
Fermat won 5 games, and Pascal won 3 games. Now, they can’t meet to play a ...
- 3,724
13
votes
3
answers
732
views
Find the TV remote
I have Alzheimer’s and suddenly forget things every 5 minutes. My super-smart younger sister has purposefully hidden the TV remote in one of two rooms. Sibling war! My favorite show is about to start, ...
- 1,340
11
votes
3
answers
917
views
Expected number of jigsaw puzzle edge pieces remaining when all four corners have been found
This is a real life puzzle. I would appreciate both an answer to the question but also an explanation as to WHY that is the answer, since I cannot work it out myself.
I enjoy doing 1000 piece jigsaw ...
- 2,488
11
votes
1
answer
987
views
Flipping coins - a solitaire game
Here is a little game I thought up - it has probably been invented before. It is inspired by this coin tossing puzzle (and the solutions, and predecessor puzzles).
I start by picking up a number (N) ...
- 2,069
8
votes
5
answers
2k
views
Three golfers and a pivotal salad
At the driving range there are three golfers A, B, and C. You know that one of them is secretly an undercover pro. The other two are amateurs. You don't know which golfer is the pro. If the pro plays ...
- 409
5
votes
1
answer
610
views
An infinite page has squares of size x*x. What is the possibility of a coin covering the vertex when thrown?
I am trying to write a puzzle. I was playing around with flipping a coin on a piece of paper with a square design. Sometimes I landed on the vertices, sometimes not. I tried to calculate the ...
- 53
15
votes
2
answers
2k
views
The Mathematics of Predicting the Future
I'm predicting the future of a deck of cards. Specifically, I have a deck of $2n$ cards: $n$ are red, and $n$ are black. The deck is shuffled uniformly randomly.
I'm dealing out the cards one by one, ...
- 7,906
6
votes
4
answers
980
views
An infinite coin-flipping game [closed]
Consider a coin-flipping game that costs $1 to play.
If heads, I win $3.
If tails, I win nothing.
I start playing this game with $100, and continue playing infinitely. Am I guaranteed to eventually ...
- 69
2
votes
2
answers
657
views
Take your seats
Given a number of persons and same number of seats, where every person has a seat assigned.
Some persons do know their seat, and, some do not know, perhaps forgot, or lost reference to, their seat.
...
- 2,404
2
votes
1
answer
299
views
Small Mario, Big Wins
This is a pretty easy problem that's suitable for people new to puzzle solving:
There's a bootleg video game called Small Mario (original name is Xiao Ma Li), which is a gambling game with different ...
- 7,944