If i have found a Conditional p.d.f of Y given X=x, how can i use this to show E(XY)=1 ? Please help, im stuck!
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Originally Posted by sj247 If i have found a Conditional p.d.f of Y given X=x, how can i use this to show E(XY)=1 ? Please help, im stuck! what is the original question?!
I can't write too much, don't wanna break the rules. I have a joint p.d.f First got to find the marginal p.d.f of X, then got to work out the conditional p.d.f of Y, given X=x. Then use that result to show E(XY)=1 Is that more clear?
You need to review the properties of conditional expectation. Refer to the link.
E(XY)=E(E(XY|X))=E(XE(Y|X)) so plug in your E(Y|X) and figure out the last expectation
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