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Math Help - expected value question

  1. #1
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    expected value question

    Hello-

    I have a quick question if anyone out there can help:

    I am told that E(x) = 8 and var (x) = 4

    the question is: determine E(y) for y=3x^2 + 2

    My answer is E(y) = 3*e(x^2) + 2

    which works out to be 3*64+2 = 194

    i realize that e(x^2) does NOT equal e(x)^2

    am i overthinking this?
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  2. #2
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    Quote Originally Posted by rogersd425 View Post
    Hello-

    I have a quick question if anyone out there can help:

    I am told that E(x) = 8 and var (x) = 4

    the question is: determine E(y) for y=3x^2 + 2

    My answer is E(y) = 3*e(x^2) + 2

    which works out to be 3*64+2 = 194

    i realize that e(x^2) does NOT equal e(x)^2

    am i overthinking this?
    Var(X) = E(X^2) - [E(X)]^2

    \Rightarrow 4 = E(X^2) - 8^2 \, ....
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