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Unformatted text preview: Practice questions for Quiz 6 to be given on October 27 ______1. Suppose that X has mean =5 and =10 and Y= 6 4X. The standard deviation of Y equals_____ _____2. Suppose that X 1 , X 2 and X 3 have mean =5 and 2 = 4 and Cov(X j , X k ) =0 for j k . Then the variance of Y= X 1 X 2 + 2X 3 equals_______ 34. Suppose we take a random sample of n=4 values of X. We let X 1 denote the first value in the sample, X 2 denote the second value, X 3 denote the 3 rd value and X 4 denote the 4 th value. Given (1) 1 = 2 = 3 = 4 = x = 2 and (2) 1 = 2 = 3 = 4 = 2 x =9. Let 4 4 1 = = i i X X . _______ 3. Regardless of the value of N, the mean value of X equals____ ________ 4. If N>> 4 then Cov(X j , X k ) = 0 for all j k and the X j are independent, so Var( X ) = ____ 1 SOLUTIONS TO QUIZ 4A ___ 40 ___ 1. Suppose that X has mean =5 and =10 and Y= 6 4X. The standard deviation of Y equals_____ Y= 64X. If Y=aX + b then 2 Y = a 2...
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 Fall '03
 Mendell

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