Calculating Unique Permutations of 30 'A's and 30 'B's or 1s and 0s

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Discussion Overview

The discussion revolves around calculating the number of unique permutations of a sequence containing 30 'A's and 30 'B's, or equivalently, 30 1s and 30 0s. Participants explore combinatorial methods to determine the total number of distinct arrangements while excluding identical permutations.

Discussion Character

  • Mathematical reasoning

Main Points Raised

  • One participant expresses curiosity about the number of permutations of 30 'A's and 30 'B's, seeking ideas on the topic.
  • Another suggests using permutations with repetition as a method for calculation.
  • A participant proposes that the number of unique permutations is given by the formula 60! / (30! x 30!).
  • It is confirmed by another participant that the proposed formula is indeed correct.
  • A further explanation is provided regarding the general formula for permutations of n items with k repeated elements, stating that the total number of permutations is n!/[(s_1)!*..*(s_k)!].
  • Another participant reiterates the original question and introduces a combinatorial perspective, stating that choosing 30 positions for 'A's in a sequence of 60 symbols can be represented as \binom{60}{30}.

Areas of Agreement / Disagreement

Participants generally agree on the mathematical approach to calculate the permutations, but there are multiple methods presented, including the factorial approach and the combinatorial approach, without a consensus on which is preferred.

Contextual Notes

Some participants reference specific mathematical formulas and methods, but there is no discussion of assumptions or limitations regarding the application of these formulas.

rsala004
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this problem has been on my mind...

how many permutations can you make with 30 'A's and 30 'B's

or rather the same question, how many unique numbers can be made from 30 1s and 30 0s

any ideas?
(excluding permutations that look identical)

thanks
 
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Use permutations with repetition.
 
it might be 60! / (30! x 30!)
 
It is.
 
In general if we have say a sequence of n items and say k objects/elements are repeated s_j times correspondingly j=1,2,...,k, then the total nr. of permutations is:

n!/[(s_1)!*..*(s_k)!]
 
rsala004 said:
this problem has been on my mind...

how many permutations can you make with 30 'A's and 30 'B's

or rather the same question, how many unique numbers can be made from 30 1s and 30 0s

any ideas?
(excluding permutations that look identical)

thanks
Here is another way to look at the problem.

You have a sequence of 60 symbols; you choose 30 of them to be A's. (The others will be B's.) This can be done in
[tex]\binom{60}{30}[/tex]
ways.
 

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