Answer+Key+to+Practice+Midterm

Answer+Key+to+Practice+Midterm - Answer Key to Practice...

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1 Chapter 9: Answer Key to Practice Midterm 9.21 a. P(X > 7) = > σ µ 5 . 1 6 7 X P = P(Z > .67) = 1 – P(Z < .67) = 1 – .7486 = .2514 b. = > ) 7 X ( P > σ µ 5 / 5 . 1 6 7 n / X P = P(Z > 1.49) = 1 – P(Z < 1.49) = 1 – .9319 = .0681 c. [P(X >7)] 5 =[.2514] 5 = .00100 9.28 P(Total number of cups > 240) = = > ) 125 / 240 X ( P = > ) 92 . 1 X ( P > σ µ 125 / 6 . 0 . 2 92 . 1 n / X P = P(Z > –1.49) = 1 P(Z < 1.49) = 1 .0681 = .9319 9.37 P( P ˆ > .10) = > 100 / ) 14 . 1 )( 14 (. 14 . 10 . n / ) p 1 ( p p P ˆ P = P(Z > –1.15) = 1 – P(Z < – 1.15) = 1 – .1251 = .8749 9.43 P( P ˆ > .28) = > 1200 / ) 25 . 1 )( 25 (. 25 . 28 . n / ) p 1 ( p p P ˆ P = P(Z > 2.40) = 1 – P(Z < 2.40) = 1 – .9918 = .0082 9.53 + > σ + σ µ µ = > 10 3 10 3 ) 15 18 ( 0 n n ) ( ) X X ( P ) 0 X X ( P 2 2 2 2 2 1 2 1 2 1 2 1 2 1 = P(Z > –2.24) = 1– P(Z < –2.24) = 1 – .0125 = .9875
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2 Chapter 10: 10.12 a. n / z x 2 / σ ± α = 500 ± 2.33(12/ 50 ) = 500 ± 3.95; LCL = 496.05, UCL = 503.95 b. n / z x 2 / σ ± α = 500 ± 1.96(12/ 50 ) = 500 ± 3.33; LCL = 496.67, UCL = 503.33 c. n / z x 2 / σ ± α = 500 ± 1.645(12/ 50 ) = 500 ± 2.79; LCL = 497.21, UCL = 502.79 d. The interval narrows. 10.51 2 2 / B z n σ = α = 2 2 10 645 . 1 × = 68 10.54 2 2 / B z n σ = α = 2 1 20 645 . 1 × = 1,083 Chapter 11: 11.4 0 H : Risky investment is more successful 1 H : Risky investment is not more successful 11.15 a. 00 . 1 25 / 5 20 21 n / x z = = σ µ = p-value = 2P(Z > 1.00) = 2(1 – .8413) = .3174 b. 00 . 2 25 / 5 20 22 n / x z = = σ µ = p-value = 2P(Z > 2.00) = 2(1 – .9772) = .0456 c. 00 . 3 25 / 5 20 23 n / x z = = σ µ = p-value = 2P(Z > 3.00) = 2(1 – .9987) = .0026
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3 d. The value of the test statistic increases and the p-value decreases. 11.56 a.
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This note was uploaded on 11/11/2011 for the course ECON 100 taught by Professor Chandle during the Spring '11 term at UC Irvine.

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Answer+Key+to+Practice+Midterm - Answer Key to Practice...

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