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Math Help - Variance of the sample mean formula.

  1. #1
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    Variance of the sample mean formula.

    Suppose you are sampling a population with mean of 1,065 and standard deviation of 500. The sample size is 100. What are the expected value and the variance of the sample mean?

    I know how to get expected value, I do not know how to get the variance of the sample mean though, the formula would be so helpful.
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  2. #2
    MHF Contributor matheagle's Avatar
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    IF the sample is i.i.d. (indep and identically distributed), then

    E(\bar X)=E(X_1)=\mu ..... I mean MOooooo

    V(\bar X)={V(X_1)\over n}={\sigma^2\over n}
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