Mastering Combinatorics: Calculating Probabilities for Liar's Dice

In summary, the conversation discusses the confusion surrounding calculating probabilities for Liar's Dice, specifically when using a wildcard. The conversation presents two approaches - a specific combinatoric approach and a general approach - but both have flaws in their calculations. The correct approach is to take into account the order of the dice rolled when counting the number of ways to get exactly one 1 or 5.
  • #1
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Probably the only area of math that really confuses me. :frown: I'm trying to calculate some probabilities for Liar's Dice. Essentially, the probabilities that a certain number of faces will appear when five dice are rolled, with one being a wildcard. If I try a specific combinatoric approach, for 5's for example, I get this. The numbers on each space represent the possible values:

Permutations that produce 0 5's: (2, 3, 4, 6)^5=4^5=1024
Permutations that produce 1 5: (1, 5)([2, 3, 4, 6]^4)=512
etc.

Already a problem emerges, as the chance of getting one 5 is higher than that of getting no 5's. If continued, it keeps dividing by two.However, if I use a general approach and ignore the wildcard property of ones, I get a (seemingly) correct answer, as when graphed it produces the familiar bell curve:
Permutations that produce 0 of anything: 5!=120 (don't quite understand the logic of this one)
Permutations that produce 1 of anything: (*)([2, 3, 4, 6]^4)=256
After that I can't figure out what I did, but here are the results:
120
256
320
80
20
1

What is the correct approach to this problem, and how to convert to probabilities?

Thanks in advance.
 
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  • #2
When you calculate how many ways you can get zero 1s or 5s you count as though you are rolling the dice one at a time and order of results matter (ie, rolling 2,2,4,4,4 is different from rolling 4,4,4,2,2). This is fine as long as you are consistent throughout, but when you count how many ways you can get exactly one 1 or 5, you don't take into account where that 1 or 5 appears in the order of dice rolled. Since there are five possible places, you should multiply 512 by 5 to get 2560.
 

Related to Mastering Combinatorics: Calculating Probabilities for Liar's Dice

1. What is combinatorics?

Combinatorics is a branch of mathematics that deals with counting and arranging objects or elements in a certain way. It involves analyzing and solving problems related to combinations, permutations, and arrangements.

2. What are some real-life applications of combinatorics?

Combinatorics has various applications in fields such as computer science, statistics, economics, and biology. Some examples include designing efficient computer algorithms, predicting outcomes in elections, and analyzing genetic sequences.

3. How is combinatorics different from probability?

While combinatorics deals with counting and arranging objects, probability deals with the likelihood of certain events occurring. Combinatorics is used to determine the total number of possible outcomes, while probability is used to calculate the chances of a specific outcome happening.

4. What is the difference between combinations and permutations?

Combinations and permutations both involve selecting a certain number of objects from a larger set. The main difference is that combinations do not consider the order of the objects, while permutations do. For example, in a combination of numbers 1, 2, and 3, the order of the numbers does not matter (1-2-3 is the same as 3-2-1). However, in a permutation, the order does matter, so 1-2-3 would be different from 3-1-2.

5. How can combinatorics be used to solve problems?

Combinatorics can be used to solve problems by breaking them down into smaller, more manageable parts. By understanding the basics of combinations, permutations, and arrangements, one can apply various strategies and formulas to solve problems involving counting and arranging objects. Practice and understanding the underlying principles are key to effectively using combinatorics to solve problems.

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