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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?

Non-transitive Dice

Stage: 3 and 4 Challenge Level: Challenge Level:2 Challenge Level:2

Here are three dice that are used to play a game for two players:
 

three dice


The red die has the numbers {1, 1, 6, 6, 8, 8}
 
The green die has the numbers {2, 2, 4, 4, 9, 9}
 
The blue die has the numbers {3, 3, 5, 5, 7, 7}
 
 




Each player chooses a different die. They roll their dice. The winner is the person whose die shows the bigger number.

Alison and Charlie are playing the game. Charlie wants to go first so Alison lets him.
Was that such a good idea?
 
Can you advise Alison on which die to choose once she knows which die Charlie has selected?


 

Notes and background
 
Dice of this sort are known as non-transitive dice. You can read more about transitivity in this article or have a go at creating your own in Dicey Dice. This spreadsheet might be useful if you want to create your own.

After you've had a go at the problem, you may be interested to read more about dice in the Plus articles Curious dice and Let 'em roll.

You may be familiar with another non-transitive game known as 'rock, paper, scissors'.