This preview shows pages 1–4. Sign up to view the full content.

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

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
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
3 d. The value of the test statistic increases and the p-value decreases. 11.56 a.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.