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Thread: Help with permutations

  1. #1
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    Help with permutations

    I am having some trouble understanding the difference between two questions. Here is the first question:

    A printed circuit board has eight different locations in which a component can be placed. If four different components are to be placed on the board, how many different designs are possible?

    Answer: P(8,4) = 1680 ways

    Second question:

    In the design of an electromechanical product, 12 components are to be stacked into a cylindrical casing in a manner that minimizes the impact of shocks. One end of the casing is designated as the bottom and the other end is the top. If all components are different, how many different designs are possible.

    Answer: 12! = 479001600 designs

    Why is it 12! and not P(12,7)?
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  2. #2
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    Re: Help with permutations

    Quote Originally Posted by vysero View Post

    Answer: 12! = 479001600 designs

    Why is it 12! and not P(12,7)?
    Where does the 7 come from??
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  3. #3
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    Re: Help with permutations

    Quote Originally Posted by vysero View Post
    I am having some trouble understanding the difference between two questions. Here is the first question:
    Second question:
    In the design of an electromechanical product, 12 components are to be stacked into a cylindrical casing in a manner that minimizes the impact of shocks. One end of the casing is designated as the bottom and the other end is the top. If all components are different, how many different designs are possible.
    Answer: 12! = 479001600 designs. Why is it 12! and not P(12,7)?
    Well there are twelve components not seven.
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  4. #4
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    Re: Help with permutations

    Oh geesh I am just being a fool sorry for the post
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