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Thread: Determine Mean and Standard Deviation from Z-Score

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    Explaining the Percentile Score of Normal Distribution




    The instructor announces that 75 percent of students scored above the mean. How do you reconcile this with the fact that, in a normal distribution, half the scores should fall below the mean and half of the scores should fall above the mean?
    Last edited by Raybob; 10-19-2014 at 04:29 PM.

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    Re: Determine Mean and Standard Deviation from Z-Score

    Your name isn't a palindrome. How do you reconcile this with the fact that if your name was just "bob" that your name would be a palindrome?
    I don't have emotions and sometimes that makes me very sad.

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    Re: Explaining the Percentile Score of Normal Distribution

    Sounds like it wasn't a normal distribution. Sounds like it was left-skewed.

    Yes, many distributions of grades follow a roughly normal distribution, but they certainly don't have to. A left-skewed distribution hints to me that it was an easy test (therefore most people did really well, and there was probably even a ceiling effect) but no matter how easy a test is there are always a handful of students who refuse to study (and therefore bomb it).

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    Re: Determine Mean and Standard Deviation from Z-Score


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    I had to create it in order to see it.
    Stop cowardice, ban guns!

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