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Homework Help: Find mean and variance of X and Y

  1. Sep 11, 2010 #1
    1. The problem statement, all variables and given/known data

    I have found the marginal distribution for X and Y from a table. (No statistical regression, just simple table)
    How should I proceed in finding mean, variance an correlation coefficient of X and y? I am computing by hand.
    Thank you,

    2. Relevant equations

    3. The attempt at a solution

    Attached Files:

  2. jcsd
  3. Sep 11, 2010 #2
    Is mean for X:


    and mean for Y is


  4. Sep 11, 2010 #3


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    Staff Emeritus
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    No. Remember the mean of a random variable is defined as

    [tex]\bar{X} = \sum_i x_i P_X(x_i)[/tex]

    It's the sum of the product of the values X can take on multiplied by probability of that value.
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