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practice4 - NE115 - Final Exam Final Practice 1. Disks of...

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NE115 - Final Exam Final Practice 1. Disks of polycarbonate plastic from a supplier are analyzed for scratch resistance and shock resistance. The results of a sample of 150 disks are summarized below: Shock Resistance High Low High 60 30 Scratch Resistance Low 40 20 What is the probability that a randomly selected disk demonstrates high resistance to scratches and/or high resistance to shocks? a) 0.67 b) 0.57 c) 0.87 d) 0.77 e) 0.97 Answer: Sample size n = 150 A: high resistance to scaratches B: high resistance to shocks Probability that a random selected disk demonstrates high resistance to scaratches and/or high resistance to shocks = P(A U B) = P(A) + P(B) - P(A ∩ B) = 100/150 + 90/150 - 60/150 = 0.87 2. An analysis of 17 pairs of data produced a least squares regression line with equation x y 2 17 + = . What is the fitted value when x = 3? a) 25 b) 24 c) 23 d) 22 e) 21 Answer: fitted value = y = 17 + 2(3) = 23
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3. A set of data pairs has the following summary statistics: , 52 , 30 = = y x S xx = 3, S yy = 2 , and r = 1/2. What is the equation for the least squares regression line in terms of x and y ? (to the nearest tenth) a) x y 3 1 = b) x y 2 1 = c) x y 4 3 5 . 27 + = d) x y 4 3 5 . 7 + = e) x y 5 2 40 + = Answer: 2247 . 1 ) 2 )( 3 ( ) 5 . 0 ( 2 2 2 2 = = = xy xy yy xx xy S S S S S r 40 ) 30 ( 408 . 0 52 408 . 0 3 2247 . 1 1 0 1 - = - = = = x y β 4. The idea of statistical inference is to a. draw conclusions about population parameter(s) based on statistic(s) calculated from sample(s). b. find distribution(s) of statistic(s).
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practice4 - NE115 - Final Exam Final Practice 1. Disks of...

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