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Math Help - Help please

  1. #1
    chancer
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    Help please

    Thanks.
    Last edited by chancer; November 23rd 2006 at 02:57 PM.
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  2. #2
    Eater of Worlds
    galactus's Avatar
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    This stuff shouldn't be a struggle even for a mathophobe.

    Assuming normal distribution.

    The formula E=z\frac{\sigma}{\sqrt{n}} gives you the margin of error.

    The z score that corresponds to a 95% CI is 1.96.

    n=144, the number in your sample.

    \overline{x}=375, the sample mean.

    {\sigma}=20, the standard deviation.

    Plug them into your formula:

    1.96\frac{20}{12}=3.2\overline{66}

    375-3.27; 375+3.27

    371.73<{\mu}<378.27

    You can say with 95% confidence that the mean price of all TV's(from the store population) will be between $371.73 and $378.26.

    Try it with the 99% CI. See what happens to the interval. Does it widen?. Narrow?.

    The z-score that corresponds to 99% is 2.575. Do you have a book with a table to look these up in?.
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  3. #3
    chancer
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    I think you underestimate your abilities.

    THANK YOU FOR YOUR HELP!!!!
    Last edited by chancer; November 23rd 2006 at 02:59 PM.
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  4. #4
    Forum Admin topsquark's Avatar
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    Chancer, you didn't happen to delete the problem you posted, did you?

    We'd prefer it if you left the problem there. Someone else might also be able to benefit from it.

    -Dan
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  5. #5
    chancer
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    I apologize.
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