DS212_HW8_Solutions

# DS212_HW8_Solutions - DS 212 Business Statistics Soorapanth...

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DS 212 Business Statistics Soorapanth Homework #8: Chapter 8 Statistical Inference: Estimation for Single Populations 8.1 a) x = 25 σ = 3.5 n = 60 95% Confidence z .025 = 1.96 n z x ± = 25 + 1.96 60 5 . 3 = 25 + 0.89 = 24.11 < µ < 25.89 b) x = 119.6 = 23.89 n = 75 98% Confidence z .01 = 2.33 n z x ± = 119.6 + 2.33 75 89 . 23 = 119.6 ± 6.43 = 113.17 < µ < 126.03 c) x = 3.419 = 0.974 n = 32 90% C.I. z .05 = 1.645 n z x ± = 3.419 + 1.645 32 974 . 0 = 3.419 ± .283 = 3.136 < µ < 3.702 d) x = 56.7 = 12.1 N = 500 n = 47 80% C.I. z . 10 = 1.28 1 - - ± N n N n z x = 56.7 + 1.28 1 500 47 500 47 1 . 12 - - = 56.7 ± 2.15 = 54.55 < µ < 58.85 8.4 n = 70 2 = 49 x = 90.4 x = 90.4 Point Estimate 94% C.I. z .03 = 1.88 n z x ± = 90.4 ± 1.88 70 49 = 90.4 ± 1.57 = 88.83 < µ < 91.97 1

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DS 212 Business Statistics Soorapanth 8.6 n = 120 x = 18.72 σ = 0.8735 99% C.I. z .005 = 2.575 x = 18.72 Point Estimate n z x ± = 18.72 ± 2.575 120 8735 . 0 = 8.72 ± .21 = 18.51 < µ < 18.93 8.7 N = 1500 n = 187 x = 5.3 years = 1.28 years 95% C.I. z .025 = 1.96 x = 5.3 years Point Estimate 1 - - ± N n N n z x = 5.3 ± 1.96 1 1500 187 1500 187 28 . 1 - - = 5.3 ± .17 = 5.13 < µ < 5.47 8.8 n = 24 x = 5.625 = 3.23 90% C.I. z . 05 = 1.645 n z x ± = 5.625 ± 1.645 24 23 . 3 = 5.625 ± 1.085 = 4.540 < µ < 6.710 8.10 n = 36 x = 2.139 = .113 x = 2.139 Point Estimate 90% C.I. z .05 = 1.645 n z x ± = 2.139 ± 1.645 36 ) 113 (. = 2.139 ± .031 = 2.108 < µ < 2.170 2
DS 212 Business Statistics Soorapanth 8.11 95% confidence interval n = 45 x = 24.533 σ = 5.124 z = + 1.96 n z x ± = 24.533 + 1.96

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## This note was uploaded on 09/10/2011 for the course DS 212 taught by Professor Saltzman during the Spring '08 term at S.F. State.

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DS212_HW8_Solutions - DS 212 Business Statistics Soorapanth...

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