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July 19th, 2009, 11:24 AM   #1
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Permutation or Combinations

I am having a hard time distinguishing which problem is a permutaion or combination.

(1) In how many ways can the three fastest runners finish a race if there are 10 runners racing.


(2) In how many distinct ways can the digits in the telephone number 778-866-5555 be arranged?
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July 20th, 2009, 03:28 PM   #2
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Re: Permutation or Combinations

(1)Combination

(2)Premutation
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August 2nd, 2009, 12:54 PM   #3
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Re: Permutation or Combinations

They are both permutations, because in case of a combination, the order doesn't matter.
And in both cases the order does matter.
An example of a combination:
How many distinct committees can you form out of 30 students?
The order in such a committe doesn't matter.
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August 4th, 2009, 07:43 AM   #4
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Re: Permutation or Combinations

Jeranimo is quite correct here.
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