Quiz7 with soln

Quiz7 with soln - its diameter Which statement is true...

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Quiz 7. NOVEMBER 2, 2003 PRINT YOUR NAME HERE_____________________ STUDENT ID ____________ 1-2 We are told that the mean diameter of the "1mm" bolts produced by the ABC Bolt Factory equals 1mm and the standard deviation equals 0.1 mm., i.e., μ = 1mm σ =0.1mm. __C __ 1. We take a sample of n=25 of the "1mm bolts" from ABC and calculate the average of these 25 bolts. We let X denote the average of a sample of 25 "1 mm bolts". Which statement is true of the distribution of X ? (a) mean equal to 1.0 mm and standard deviation of 5 mm. (b) mean equal to 1.0 mm and standard deviation of 0.1 mm (c) mean equal to 1.0 mm. and standard deviation of 0.02 mm (d) mean equal to 1.0 mm and standard deviation of 0.0004 mm. __B __ 2. We take a "1 mm bolt" (made by ABC) at random. Here X denotes
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Unformatted text preview: its diameter. Which statement is true about the distribution of X? (a) mean equal to 1.0 mm and standard deviation of 5 mm. (b) mean equal to 1.0 mm. and standard deviation of 0.1mm. (c) mean equal to 1.0 mm and standard deviation of 0.02 mm. (d) mean equal to 1.99 lb. and standard deviation of 0.004 mm. 4.541 _ 4. Find t such that P(T 3 < t) = 0.99. Here T 3 denotes a random variable with the"t" p.d.f. and ν =3 . _5/3 or 1.67 _ 5. Y j ~N(2,9) for j=1,2…25. The Y j are all pairwise independent. That is, μ Y =2, σ Y =3 n=25 Cov(Y k , Y t )=0 for all k and t. Let 25 25 1 ∑ = = k k Y Y . So SE( Y )=3/5 =0.6 Pr( Y < 3) = Φ ( Z ) ; Z = ____________ 3 2 5 1.67 3/ 5 3 Z-= = = 1...
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