Instructor’s Solutions Manual Probability And Statistical .

Instructor’s SolutionsManualProbability andStatistical InferenceEighth EditionRobert V. HoggUniversity of IowaElliot A. TanisHope College

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ContentsPreface1 Probability1.1 Basic Concepts . . . . .1.2 Properties of Probability1.3 Methods of Enumeration1.4 Conditional Probability1.5 Independent Events . .1.6 Bayes’s Theorem . . . .v.11234672 Discrete Distributions2.1 Random Variables of the Discrete Type . . . .2.2 Mathematical Expectation . . . . . . . . . . . .2.3 The Mean, Variance, and Standard Deviation .2.4 Bernoulli Trials and the Binomial Distribution2.5 The Moment-Generating Function . . . . . . .2.6 The Poisson Distribution . . . . . . . . . . . .111115161922243 Continuous Distributions3.1 Continuous-Type Data . . . . . . . . . . . .3.2 Exploratory Data Analysis . . . . . . . . . .3.3 Random Variables of the Continuous Type .3.4 The Uniform and Exponential Distributions3.5 The Gamma and Chi-Square Distributions .3.6 The Normal Distribution . . . . . . . . . . .3.7 Additional Models . . . . . . . . . . . . . .27273037454850544 Bivariate Distributions4.1 Distributions of Two Random Variables4.2 The Correlation Coefficient . . . . . . .4.3 Conditional Distributions . . . . . . . .4.4 The Bivariate Normal Distribution . . .5757596166.69. . . . . . . 69. . . . . . . 73. . . . . . . 76. . . . . . . 79. . . . . . . 81. . . . . . . 84. . . . . . . 86.5 Distributions of Functions of Random Variables5.1 Functions of One Random Variable . . . . . . . . . . . . .5.2 Transformations of Two Random Variables . . . . . . . .5.3 Several Independent Random Variables . . . . . . . . . .5.4 The Moment-Generating Function Technique . . . . . . .5.5 Random Functions Associated with Normal Distributions5.6 The Central Limit Theorem . . . . . . . . . . . . . . . . .5.7 Approximations for Discrete Distributions . . . . . . . . .iii.

iv6 Estimation6.1 Point Estimation . . . . . . . . . . . . . . . .6.2 Confidence Intervals for Means . . . . . . . .6.3 Confidence Intervals for the Difference of Two6.4 Confidence Intervals for Variances . . . . . .6.5 Confidence Intervals for Proportions . . . . .6.6 Sample Size . . . . . . . . . . . . . . . . . . .6.7 A Simple Regression Problem . . . . . . . . .6.8 More Regression . . . . . . . . . . . . . . . . . . . . . .Means. . . . . . . . . . . . . . . .91. 91. 94. 95. 97. 99. 100. 101. 1077 Tests of Statistical Hypotheses7.1 Tests about Proportions . . . . . . . . . . . .7.2 Tests about One Mean . . . . . . . . . . . . .7.3 Tests of the Equality of Two Means . . . . .7.4 Tests for Variances . . . . . . . . . . . . . . .7.5 One-Factor Analysis of Variance . . . . . . .7.6 Two-Factor Analysis of Variance . . . . . . .7.7 Tests Concerning Regression and Correlation.1151151171201231241271288 Nonparametric Methods8.1 Chi-Square Goodness-of-Fit Tests . . . . . . . . . . .8.2 Contingency Tables . . . . . . . . . . . . . . . . . . .8.3 Order Statistics . . . . . . . . . . . . . . . . . . . . .8.4 Distribution-Free Confidence Intervals for Percentiles8.5 The Wilcoxon Tests . . . . . . . . . . . . . . . . . .8.6 Run Test and Test for Randomness . . . . . . . . . .8.7 Kolmogorov-Smirnov Goodness of Fit Test . . . . . .8.8 Resampling Methods . . . . . . . . . . . . . . . . . .131131135136138140144147149.9 Bayesian Methods1579.1 Subjective Probability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1579.2 Bayesian Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1589.3 More Bayesian Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15910 Some Theory10.1 Sufficient Statistics . . . . . . . . . . . .10.2 Power of a Statistical Test . . . . . . . .10.3 Best Critical Regions . . . . . . . . . . .10.4 Likelihood Ratio Tests . . . . . . . . . .10.5 Chebyshev’s Inequality and Convergence10.6 Limiting Moment-Generating Functions10.7 Asymptotic Distributions of MaximumLikelihood Estimators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .in Probability. . . . . . . . .161161162166168169170. . . . . . . . . . . . . . . . . . . . . . . . . . 17111 Quality Improvement Through Statistical Methods11.1 Time Sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.2 Statistical Quality Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.3 General Factorial and 2k Factorial Designs . . . . . . . . . . . . . . . . . . . . . . . . .173173176179

PrefaceThis solutions manual provides answers for the even-numbered exercises in Probability and StatisticalInference, 8th edition, by Robert V. Hogg and Elliot A. Tanis. Complete solutions are given for mostof these exercises. You, the instructor, may decide how many of these answers you want to makeavailable to your students. Note that the answers for the odd-numbered exercises are given in thetextbook.All of the figures in this manual were generated using Maple, a computer algebra system. Mostof the figures were generated and many of the solutions, especially those involving data, were solvedusing procedures that were written by Zaven Karian from Denison University. We thank him forproviding these. These procedures are available free of charge for your use. They are available onthe CD-ROM in the textbook. Short descriptions of these procedures are provided in the “MapleCard” that is on the CD-ROM. Complete descriptions of these procedures are given in Probabilityand Statistics: Explorations with MAPLE, second edition, 1999, written by Zaven Karian and ElliotTanis, published by Prentice Hall (ISBN 0-13-021536-8).REMARK Note that Probability and Statistics: Explorations with MAPLE, second edition, writtenby Zaven Karian and Elliot Tanis, is available for download from Pearson Education’s online catalog.It has been slightly revised and now contains references to several of the exercises in the 8th editionof Probability and Statistical Inference. Our hope is that this solutions manual will be helpful to each of you in your teaching. If you findan error or wish to make a suggestion, send these to Elliot Tanis at tanis@hope.edu and he will postcorrections on his web page, http://www.math.hope.edu/tanis/.R.V.H.E.A.T.v

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Chapter 1Probability1.1Basic Concepts1.1-2 (a) S {bbb, gbb, bgb, bbg, bgg, gbg, ggb, ggg};(b) S {female, male};(c) S {000, 001, 002, 003, . . . , 999}.1.1-4 (a)Clutch 410.300.250.200.150.100.052468101214Figure 1.1–4: Clutch sizes for the common gallinule(c) 9.1x

2Section 1.2 Properties of Probability1.1-6 (a)No. 040.022468 10 12 14 16 18 20 22 24xFigure 1.1–6: Number of boxes of cereal1.1-8 (a) f (1) 2332, f (2) , f (3) , f (4) .101010101.1-10 This is an experiment.1.1-12 (a) 50/204 0.245; 93/329 0.283;(b) 124/355 0.349; 21/58 0.362;(c) 174/559 0.311; 114/387 0.295;(d) Although James’ batting average is higher that Hrbek’s on both grass and artificialturf, Hrbek’s is higher over all. Note the different numbers of at bats on grass andartificial turf and how this affects the batting averages.1.2Properties of Probability1.2-2 Sketch a figure and fill in the probabilities of each of the disjoint sets.Let A {insure more than one car}, P (A) 0.85.Let B {insure a sports car}, P (B) 0.23.Let C {insure exactly one car}, P (C) 0.15.It is also given that P (A B) 0.17. Since P (A C) 0, it follows thatP (A B C 0 ) 0.17. Thus P (A0 B C 0 ) 0.06 and P (A0 B 0 C) 0.09.1.2-4 (a) S {HHHH, HHHT, HHTH, HTHH, THHH, HHTT, HTTH, TTHH,HTHT, THTH, THHT, HTTT, THTT, TTHT, TTTH, TTTT};(b) (i) 5/16, (ii) 0, (iii) 11/16, (iv) 4/16, (v) 4/16, (vi) 9/16, (vii) 4/16.1.2-6 (a) 1/6;(b) P (B) 1 P (B 0 ) 1 P (A) 5/6;(c) P (A B) P (S) 1.

Section 1.3 Methods of Enumeration1.2-8 (a) P (A B) 0.4 0.5 0.3 0.6;(b)AP (A)0.4P (A B) (A B 0 ) (A B) P (A B 0 ) P (A B) P (A B 0 ) 0.3 0.1;(c) P (A0 B 0 ) P [(A B)0 ] 1 P (A B) 1 0.3 0.7.1.2-10 Let A {lab work done}, B {referral to a specialist},P (A) 0.41, P (B) 0.53, P ([A B]0 ) 0.21.P (A B) P (A) P (B) P (A B)0.79 0.41 0.53 P (A B)P (A B) 0.41 0.53 0.79 0.15.1.2-12A B C A (B C)P (A B C) P (A) P (B C) P [A (B C)] P (A) P (B) P (C) P (B C) P [(A B) (A C)] P (A) P (B) P (C) P (B C) P (A B) P (A C) P (A B C).1.2-14 (a) 1/3; (b) 2/3; (c) 0; (d) 1/2.1.2-16 (a) S {(1, 2), (1, 3), (1, 4), (1, 5), (2, 3), (2, 4), (2, 5), (3, 4), (3, 5), (4, 5)};(b) (i) 1/10; (ii) 5/10. 2[r r( 3/2)]3 1 .1.2-18 P (A) 2r21.2-20 Note that the respective probabilities are p0 , p1 p0 /4, p2 p0 /42 , . . . Xp0 14kk 0p01 1/4p0 1 341 p 0 p1 1 1.3115 .1616Methods of Enumeration1.3-2 (4)(3)(2) 24.1.3-4 (a) (4)(5)(2) 40; (b) (2)(2)(2) 8.µ ¶61.3-6 (a) 4 80;3(b) 4(26 ) 256;(c)1.3-89 P4(4 1 3)! 20.(4 1)!3! 9! 3024.5!3

4Section 1.4 Conditional Probability1.3-10 S { HHH, HHCH, HCHH, CHHH, HHCCH, HCHCH, CHHCH, HCCHH,CHCHH, CCHHH, CCC, CCHC, CHCC, HCCC, CCHHC, CHCHC,HCCHC, CHHCC, HCHCC, HHCCC } so there are 20 possibilities.1.3-12 3 · 3 · 212 36, 864.¶¶ µµn 1n 1 1.3-14r 1r(n 1)!(n 1)! r!(n 1 r)! (r 1)!(n r)! (n r)(n 1)! r(n 1)!n! r!(n r)!r!(n r)!µ ¶n µ ¶nXXnr nrn rn( 1)(1 1) .( 1) (1) rrr 0r 0 1.3-160 2n (1 1)n n µ ¶Xnrr 01.3-18µnn1 , n 2 , . . . , n s¶(1)r (1)n r n µ ¶Xnr 0r.¶¶µ¶µ¶µn n1 · · · ns 1n n 1 n n 1 n2···nsn3n2 µ n!(n n1 )!·n1 !(n n1 )! n2 !(n n1 n2 )!nn1· µ ¶n.r(n n1 n2 · · · ns 1 )!(n n1 n2 )!···n3 !(n n1 n2 n3 )!ns !0!n!.n1 !n2 ! . . . ns !¶52 19102, 4866µ ¶1.3-20 (a) 0.2917;52351, 3259µ ¶µ ¶µ ¶µ ¶µ ¶µ ¶µ ¶19 10 7 3 5 2 67, 6951 0 1 0 223µ ¶ 0.00622.(b) 521, 236, 6649µ ¶451.3-22 886,163,135.36µ1.4193¶µConditional Probability1.4-2 (a)1041;1456(b)392;633(c)649.823(d) The proportion of women who favor a gun law is greater than the proportion of menwho favor a gun law.

5Section 1.4 Conditional Probability1.4-4 (a) P (HH) (b) P (HC) 13 121· ;52 511713 1313· ;52 51204(c) P (Non-Ace Heart, Ace) P (Ace of Hearts, Non-Heart Ace) 12 41 3511· · .52 51 52 5152 · 51521.4-6 Let A {3 or 4 kings}, B {2, 3, or 4 kings}.P (A B) P (A B)N (A) P (B)N (B)µ ¶µ ¶ µ ¶µ ¶4 484 48 9 ¶µ ¶µ ¶µ 3¶ 10µ ¶µ 4¶ µ 0.170.4 484 484 48 2 113 10491.4-8 Let H {died from heart disease}; P {at least one parent had heart disease}.P (H P 0 ) 110N (H P 0 ) .N (P 0 )6483 2 11·· ;20 19 181140µ ¶µ ¶3 171121µ ¶ ·(b) ;20177603¶µ ¶µ1739X3512 2k 2µ ¶(c) 0.4605.·2020 2k76k 12k1.4-10 (a)(d) Draw second. The probability of winning in 1 0.4605 0.5395.µ ¶µ ¶µ ¶µ ¶2 82 81211 40 51.4-12 µ ¶ · µ ¶ · .1010555558, 808, 97552 51 50 49 48 47····· 0.74141;52 52 52 52 52 5211, 881, 376(b) P (A0 ) 1 P (A) 0.25859.1.4-14 (a) P (A) 1.4-16 (a) It doesn’t matter because P (B1 ) (b) P (B) 1.4-1812 on each draw.189233 5 2 4· · .5 8 5 840111, P (B5 ) , P (B18 ) ;181818