(adsbygoogle = window.adsbygoogle || []).push({}); 1. Let N and T be the number of users logged on and the time until the next log-off. The joint probability of N and T is given by P(N=η, X≤t) = (1-ρ)ρ^{η-1}(1-e^{-ηλt}) for η=1,2,...;t>0.) Find the correlation and covariance of N and T.

2. COV(X,Y) = E[XY]-E[X]E[Y]

ρ_{X,Y} = (E[XY]-E[X]E[Y])/(σ_{X}σ_{Y})

E[XY] = ∫∫ xy f_{XY}(x,y) dx dy

3. I do not know how to find the expected value from the joint PDF and was hoping for some guidance.

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# Homework Help: Covariance/ Correlation Calculation

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