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  1. #1
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    What does the X mean in the MTBF eauqtion?

    Hi, Gurus,
    Attachment is one MTBF picture searched in the Chinese webpage.
    There is an example in the picture:
    Say confidence=90%, and MTBF=300 hours, and failure number is 3,
    then
    T=0.5*(X0.9(2*3+2))^2*300=524 hours.
    Here what confused me is how can they calculated 524 hours?
    What does X mean? Integration?
    Best,
    Tony Liu

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  2. #2
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    Re: What does the X mean in the MTBF eauqtion?

    Hi,
    Now I found it is "chi-square" distribution.
    Attachment is one chart for this distribution.
    Say 90% probability, and 3 failures as 3 freedom, then it is 0.58,
    so T=(0.58)*8*0.5*300=696 hours, how the aforesaid picture calculated 500 hours?
    So confused.
    Pls comment.
    Thanks.
    Best,
    Tony Liu



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