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VERY URGENT !!!! Suppose that X and Y are random samples of observations from a population...

VERY URGENT !!!! Suppose that X and Y are random samples of observations from a population with mean μ and variance σ2.

Consider the following two unbiased point estimators of μ.

A = (7/4)X - (3/4)Y    B = (1/3)X + (2/3)Y

[Give your answers as ratio (eg: as number1 / number2 ) and DO NOT make any cancellation]  

1.    Find variance of A. Var(A) =(Answer)*σ2

2.    Find variance of B. Var(B) =(Answer)*σ2

3. Efficient and unbiased point estimator for μ is (Answer)

Math   Statistics-And-Probability   
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