Why do combination and permutation have different rules for order?

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SUMMARY

The discussion clarifies the distinction between combinations and permutations using a practical example involving a dog show with 5 finalists. The correct approach to determine the number of ways to award "Best in Show" and "Honorable Mention" is through permutations, as the order of awards matters. The calculation is represented as 5P2, resulting in 20 distinct arrangements. Participants emphasize the importance of understanding these concepts through established definitions rather than guessing.

PREREQUISITES
  • Understanding of basic probability concepts
  • Familiarity with factorial notation (n!)
  • Knowledge of the difference between combinations and permutations
  • Ability to perform basic arithmetic operations
NEXT STEPS
  • Study the mathematical definitions of combinations and permutations
  • Practice solving problems involving permutations using the formula nPr = n!/(n-r)!
  • Explore real-world applications of combinations and permutations in probability theory
  • Review examples of both combinations and permutations to solidify understanding
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Students, educators, and anyone interested in mastering probability concepts, particularly those focusing on combinatorial mathematics.

nycmathdad
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At a recent dog show, there were 5 finalists. One of the finalists was awarded "Best in Show" and another finalist was awarded "Honorable Mention." In how many different ways could the two awards be given out?

The words "how many ways" reminds of probability. I just don't recall if this is a combination or a permutation.

I will take a guess and say this is a combination problem.

The set up is 5C2.

You say?
 
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nycmathdad said:
At a ...
I will take a guess and say this is a combination problem.

The set up is 5C2.

You say?
I say stop guessing.
You have a textbook.
Look it up laddie.
 
Personally, I would not worry about what it is called! There are 5 dogs anyone of which could be declared "best in show". Once that had been chosen, there are 4 dogs left that could be chosen "honorable mention".

There are a total of 5(4)= 20 ways that could be done.

(Since order, which dog is "best in show" and which is "honorable mention", is relevant, this is a "permutation" problem but, as I say, that is really not important.)
 
Country Boy said:
Personally, I would not worry about what it is called! There are 5 dogs anyone of which could be declared "best in show". Once that had been chosen, there are 4 dogs left that could be chosen "honorable mention".

There are a total of 5(4)= 20 ways that could be done.

(Since order, which dog is "best in show" and which is "honorable mention", is relevant, this is a "permutation" problem but, as I say, that is really not important.)

Are you saying that that 5C2 should be 5P2?

Let me see.

5P2 = 5!/(5 - 2)!

5P2 = 120/(3)!

5P2 = 120/6

5P2 = 20 ways.

When it comes to combination versus permutation, in terms of combination order does matter. Order does not matter in terms of permutation. Can you explain why that is the case using a simple math example for both cases?
 
nycmathdad said:
...
When it comes to combination versus permutation, in terms of combination order does matter. Order does not matter in terms of permutation. Can you explain why that is the case using a simple math example for both cases?
There you go again asking volunteer helpers to post a war and peace explanation for something that you could just read from your textbook. Read your book. Reading is good for you.
 

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