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Unformatted text preview: Stat 401G: Quiz 1 Homework Solutions For Friday September 9, 2011 Problem 1.43 Part A : E (¯ y ) = μ = 0 . 10 and V ar (¯ y ) = σ 2 n = . 01 50 = 0 . 002 . We are usually interested in SD (¯ y ) = σ √ n = . 1 √ 50 ≈ . 01414 . In terminology used in class, E (¯ y ) and V ar (¯ y ) are respectively the mean and variance of the sampling distribution of ¯ y. Part B : For a reasonably large sample size, the central limit theorem says that the sampling distribution of ¯ y should be approximately normally distributed even though the population from which the sample is drawn is not normal. I might use the notations ¯ y . ∼ N μ, σ √ n to say that ¯ y is approximately normally distributed. Part C : z = . 13 . 1 . 01414 = 2 . 12. P ( ¯ Y > . 13 ) = P ( Z > 2 . 12) = 0 . 5 . 4830 = 0 . 0170 Problem 1.45 Part A : You will use the formula ¯ y ± t . 01 / 2 s √ n where the t value is based on n 1 = 71 degrees of freedom. This number of degrees of freedom is not on your table. In lab, we will show you how to use the computer to get this value which is 2table....
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This note was uploaded on 02/06/2012 for the course STAT 401 taught by Professor Shelley during the Spring '08 term at Iowa State.
 Spring '08
 Shelley
 Variance

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