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Math Help - how did they get this?

  1. #1
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    how did they get this?

    mean=1.5 standard deviation=10 n=20 sample mean=1.2

    1.2-1.5 = 1.3 10/4.47213 =2.236 1.3/2.236= -0.134
    p value= .3669?

    but i get .4483
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  2. #2
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    Quote Originally Posted by crashuk View Post
    mean=1.5 standard deviation=10 n=20 sample mean=1.2

    1.2-1.5 = 1.3 10/4.47213 =2.236 1.3/2.236= -0.134
    p value= .3669?

    but i get .4483
    I think you had better give us more information about this problem, otherwise we will just be guessing.

    But consider looking your value up in a table of the t-distribution with 19 degrees of freedom rather than the normal table.

    RonL
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  3. #3
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    Quote Originally Posted by CaptainBlack View Post
    I think you had better give us more information about this problem, otherwise we will just be guessing.

    But consider looking your value up in a table of the t-distribution with 19 degrees of freedom rather than the normal table.

    RonL
    thats all that was given
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  4. #4
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    Quote Originally Posted by crashuk View Post
    mean=1.5 standard deviation=10 n=20 sample mean=1.2

    1.2-1.5 = 1.3 10/4.47213 =2.236 1.3/2.236= -0.134
    p value= .3669?

    but i get .4483
    There must be more to the question than just this! And what have I said about the setting out ....!?

    Is it the sample standard deviation or the population standard deviation?

    If the latter, than the z-statistic is appropriate and the p-value is 0.4467 (correct to four decimal places).

    If the former, than the t-statistic is appropriate (provided the data come from a normal population) and the p-value is 0.4474 (correct to four decimal places).
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