Let X be a random variable taking the values ±1 and ±2 with equal probability. Let Y = X^2. How do i calculate the Cov(X,Y)? i'm not sure which formula to use because ive tried Cov(X,Y) = E(XY)-(E(X)E(Y)) but that equals 0
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i think i might of figured this one out the covariance is 0 because the random variables are independent?
Originally Posted by dexza666 i think i might of figured this one out the covariance is 0 because the random variables are independent? Yes ! $\displaystyle \text{X and Y are independent } \Longleftrightarrow \text{ cov}(X,Y)=0$ But here, I'm not sure they're independent... you gotta prove it !
Last edited by Moo; Sep 5th 2008 at 11:38 PM.
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