# Quiz4 - Quiz 4 Let Xi i=1 2 n be a random sample from a...

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Quiz 4 , = , , …, , Let Xi i 1 2 n be a random sample from a population with mean . μ1 and variance σ12 , = , , …, , Let Yi i 1 2 n be a random sample from a population with mean . μ2 and variance σ22 1. Suppose these two samples are independent, please derive the expression for - ; varX Y 2. Suppose these two samples are paired in that ( , )≡ corr Xi Yi ρ , please derive the expression for - . varX Y Solution: 1. - = + = + varX Y varX varY σ12n σ22n
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