Other tags that relate to X-dice
Equally likely outcomes. Spreadsheets. Conditional probability. Mathematical modelling. Tree diagrams. Experimental probability. Combining probabilities. Biology. Probability. Theoretical probability.There are 41 results
Broad Topics > Decision Mathematics and Combinatorics > Combinatorics
In a Box
Age 14 to 16
Challenge Level
Chris and Jo put two red and four blue ribbons in a box. They each pick a ribbon from the box without looking. Jo wins if the two ribbons are the same colour. Is the game fair?
Snooker
Age 16 to 18
Challenge Level
A player has probability 0.4 of winning a single game. What is his probability of winning a 'best of 15 games' tournament?
Snooker Frames
Age 16 to 18
Challenge Level
It is believed that weaker snooker players have a better chance of winning matches over eleven frames (i.e. first to win 6 frames) than they do over fifteen frames. Is this true?
Scratch Cards
Age 14 to 16
Challenge Level
To win on a scratch card you have to uncover three numbers that add up to more than fifteen. What is the probability of winning a prize?
Stage 5 Cipher Challenge
Age 16 to 18
Challenge Level
Can you crack these very difficult challenge ciphers? How might you systematise the cracking of unknown ciphers?
The Eternity Puzzle
Age 16 to 18
A big prize was offered for solving The Eternity Puzzle, a jigsaw with no picture and every piece is the same on both sides. The finished result forms a regular dodecagon (12 sided polygon).
Molecular Sequencer
Age 14 to 18
Challenge Level
Investigate the molecular masses in this sequence of molecules and deduce which molecule has been analysed in the mass spectrometer.
An Introduction to Computer Programming and Mathematics
Age 16 to 18
This article explains the concepts involved in scientific mathematical computing. It will be very useful and interesting to anyone interested in computer programming or mathematics.
Penta Colour
Age 14 to 16
Challenge Level
In how many different ways can I colour the five edges of a pentagon red, blue and green so that no two adjacent edges are the same colour?
Cube Net
Age 16 to 18
Challenge Level
How many tours visit each vertex of a cube once and only once? How many return to the starting point?
Magic W Wrap Up
Age 16 to 18
Challenge Level
Prove that you cannot form a Magic W with a total of 12 or less or with a with a total of 18 or more.
Magic Caterpillars
Age 14 to 18
Challenge Level
Label the joints and legs of these graph theory caterpillars so that the vertex sums are all equal.
W Mates
Age 16 to 18
Challenge Level
Show there are exactly 12 magic labellings of the Magic W using the numbers 1 to 9. Prove that for every labelling with a magic total T there is a corresponding labelling with a magic total 30-T.
Links and Knots
Age 14 to 18
Some puzzles requiring no knowledge of knot theory, just a careful inspection of the patterns. A glimpse of the classification of knots, prime knots, crossing numbers and knot arithmetic.
N000ughty Thoughts
Age 14 to 16
Challenge Level
How many noughts are at the end of these giant numbers?
Walkabout
Age 14 to 16
Challenge Level
A walk is made up of diagonal steps from left to right, starting at the origin and ending on the x-axis. How many paths are there for 4 steps, for 6 steps, for 8 steps?
Russian Cubes
Age 14 to 16
Challenge Level
I want some cubes painted with three blue faces and three red faces. How many different cubes can be painted like that?
Tangles
Age 11 to 16
A personal investigation of Conway's Rational Tangles. What were the interesting questions that needed to be asked, and where did they lead?
Euler's Officers
Age 14 to 16
Challenge Level
How many different ways can you arrange the officers in a square?
Olympic Magic
Age 14 to 16
Challenge Level
in how many ways can you place the numbers 1, 2, 3 … 9 in the nine regions of the Olympic Emblem (5 overlapping circles) so that the amount in each ring is the same?
Snowman
Age 14 to 16
Challenge Level
All the words in the Snowman language consist of exactly seven letters formed from the letters {s, no, wm, an). How many words are there in the Snowman language?
Binomial Coefficients
Age 14 to 18
An introduction to the binomial coefficient, and exploration of some of the formulae it satisfies.
One Basket or Group Photo
Age 7 to 18
Challenge Level
Libby Jared helped to set up NRICH and this is one of her favourite problems. It's a problem suitable for a wide age range and best tackled practically.
Symmetric Tangles
Age 14 to 16
The tangles created by the twists and turns of the Conway rope trick are surprisingly symmetrical. Here's why!
Doodles
Age 14 to 16
Challenge Level
Draw a 'doodle' - a closed intersecting curve drawn without taking pencil from paper. What can you prove about the intersections?
Lost in Space
Age 14 to 16
Challenge Level
How many ways are there to count 1 - 2 - 3 in the array of triangular numbers? What happens with larger arrays? Can you predict for any size array?
Deep Roots
Age 14 to 16
Challenge Level
Find integer solutions to: $\sqrt{a+b\sqrt{x}} + \sqrt{c+d.\sqrt{x}}=1$
Postage
Age 14 to 16
Challenge Level
The country Sixtania prints postage stamps with only three values 6 lucres, 10 lucres and 15 lucres (where the currency is in lucres).Which values cannot be made up with combinations of these postage. . . .
Transitivity
Age 16 to 18
Suppose A always beats B and B always beats C, then would you expect A to beat C? Not always! What seems obvious is not always true. Results always need to be proved in mathematics.
Knight Defeated
Age 14 to 16
Challenge Level
The knight's move on a chess board is 2 steps in one direction and one step in the other direction. Prove that a knight cannot visit every square on the board once and only (a tour) on a 2 by n board. . . .
Magic W
Age 14 to 16
Challenge Level
Find all the ways of placing the numbers 1 to 9 on a W shape, with 3 numbers on each leg, so that each set of 3 numbers has the same total.
Ordered Sums
Age 14 to 16
Challenge Level
Let a(n) be the number of ways of expressing the integer n as an ordered sum of 1's and 2's. Let b(n) be the number of ways of expressing n as an ordered sum of integers greater than 1. (i) Calculate. . . .
Counting Binary Ops
Age 14 to 16
Challenge Level
How many ways can the terms in an ordered list be combined by repeating a single binary operation. Show that for 4 terms there are 5 cases and find the number of cases for 5 terms and 6 terms.
NRICH is part of the family of activities in the Millennium Mathematics Project.