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virtus

Eight keys are placed on a key ring. How many different arrangements are possible if they are all different

  • one year ago
  • one year ago

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  1. IllasMcKay
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    Pairs or ....

    • one year ago
  2. virtus
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    what do you mean?

    • one year ago
  3. IllasMcKay
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    just wait my Friend

    • one year ago
  4. sauravshakya
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    8 factorial

    • one year ago
  5. IllasMcKay
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    |dw:1342271877443:dw| then 8 factorial as @sauravshakya

    • one year ago
  6. virtus
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    my solution book says the answer is 7!/2

    • one year ago
  7. virtus
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    @myko where does the 2 come from?

    • one year ago
  8. myko
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    |dw:1342272266287:dw| |dw:1342272292346:dw| is the same in this case

    • one year ago
  9. myko
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    no, you right. The right answer is 7!/2

    • one year ago
  10. virtus
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    yes i thought so, because it is (n-1)!

    • one year ago
  11. mukushla
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    The total number of n objects, arranged in a circle which can be flipped over without making a new arrangement is: \[\frac{(n-1)!}{2}\]

    • one year ago
  12. virtus
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    thank you@mukushla

    • one year ago
  13. myko
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    it is (n-1)! and not n!, because there is no reference point. The reference point is the first key you put, so it's has to be rested from the total number of left posibilties. It is later devided by 2, becouse the ring can flip, so symetric permutations become the same

    • one year ago
  14. virtus
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    btw @myko does this rule apply to sitting in a circle arrangements

    • one year ago
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