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Math Help - Help with standard deviation & expected value please

  1. #1
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    Help with standard deviation & expected value please

    x -5 -1 2 7 10
    P(x)0.15 0.08 0.22 0.18 0.37

    Determine the expected value of x.

    Determine the standard deviation of x.
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  2. #2
    Senior Member BAdhi's Avatar
    Joined
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    Gampaha, Sri Lanka
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    Re: Help with standard deviation & expected value please

    Stick to the definitions,

    E(X)=\Sigma_{i=1}^{n}x_iP(x_i)}

    and

    SD(X)=\sqrt{\Sigma_{i=1}^{n}\left[x_i-E(X)\right]^2P(x_i)}} or

    SD(X)=\sqrt{E(X^2)-E(X)^2}

    Next time please show where you cannot understand, because for me this seems quite basics
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