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Math Help - finding the value of x

  1. #1
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    finding the value of x

    Hello, how to I find the value of x? The problem I'm doing has a graph of 160< x < 168 with the mean of 168 and the standard deviation of 5.54. I'm having a hard time with finding what x should be. I'm supposed to assume the variable x is normally distributed. Thank you.
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  2. #2
    Eater of Worlds
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    It would appear you have two x values. I don't know what you mean by finding the x values.

    I am guessing you need to find the area under the standard normal curve.

    Just use the table and subtract the two values.

    z=\frac{x-{\mu}}{\sigma}=\frac{168-168}{5.54}=0

    \frac{160-168}{5.54}=-1.444...

    From the table:

    z=0 corresponds to the mean and it's value is 0.5

    z=-1.444... corresponds to 0.07436...

    0.5-0.07436=0.425

    Here's a graph of your region. I assume this is what you're meaning.
    Last edited by galactus; November 24th 2008 at 05:39 AM.
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