Probabilidades Y Esta

INSTRUCTORfS
SOLUTION MANUAL
KEYING YE AND SHARON MYERS
for
PROBABILITY & STATISTICS
FOR ENGINEERS & SCIENTISTS
EIGHTH EDITION
WALPOLE, MYERS, MYERS, YE

Contents
1 Introduction to Statistics and Data Analysis 1
2 Probability 11
3 Random Variables and Probability Distributions 29
4 Mathematical Expectation 45
5 Some Discrete Probability Distributions 59
6 Some ContinuousProbability Distributions 71
7 Functions of Random Variables 85
8 Fundamental Sampling Distributions and Data Descriptions 91
9 One- and Two-Sample Estimation Problems 103
10 One- and Two-Sample Tests of Hypotheses 121
11 Simple Linear Regression and Correlation 149
12 Multiple Linear Regression and Certain Nonlinear Regression Models 171
13 One-Factor Experiments: General 185
14 FactorialExperiments (Two or More Factors) 213
15 2k Factorial Experiments and Fractions 237
16 Nonparametric Statistics 257
iii
iv CONTENTS
17 Statistical Quality Control 273
18 Bayesian Statistics 277
Chapter 1
Introduction to Statistics and Data
Analysis
1.1 (a) 15.
(b) Px = 1
15 (3.4 + 2.5 + 4.8 + E E E + 4.8) = 3.787.
(c) Sample median is the 8th value, after the data is sorted from smallestto largest:
3.6.
(d) A dot plot is shown below.
2.5 3.0 3.5 4.0 4.5 5.0 5.5
(e) After trimming total 40% of the data (20% highest and 20% lowest), the data
becomes:
2.9 3.0 3.3 3.4 3.6
3.7 4.0 4.4 4.8
So. the trimmed mean is
Pxtr20 =
1
9
(2.9 + 3.0 + E E E + 4.8) = 3.678.
1.2 (a) Mean=20.768 and Median=20.610.
(b) Pxtr10 = 20.743.
(c) A dot plot is shown below.
18 19 20 21 2223
1
2 Chapter 1 Introduction to Statistics and Data Analysis
1.3 (a) A dot plot is shown below.
200 205 210 215 220 225 230
In the figure, g~h represents the gNo agingh group and g.h represents the gAgingh
group.
(b) Yes; tensile strength is greatly reduced due to the aging process.
(c) MeanAging = 209.90, and MeanNo aging = 222.10.
(d) MedianAging = 210.00, and MedianNo aging =221.50. The means and medians for
each group are similar to each other.
1.4 (a) PXA = 7.950 and .XA = 8.250;
PX
B = 10.260 and .XB = 10.150.
(b) A dot plot is shown below.
6.5 7.5 8.5 9.5 10.5 11.5
In the figure, g~h represents company A and g.h represents company B. The
steel rods made by company B show more flexibility.
1.5 (a) A dot plot is shown below.
.10 0 10 20 30 40
Inthe figure, g~h represents the control group and g.h represents the treatment
group.
(b) PXControl = 5.60, .XControl = 5.00, and PXtr(10);Control = 5.13;
PX
Treatment = 7.60, .XTreatment = 4.50, and PXtr(10);Treatment = 5.63.
(c) The difference of the means is 2.0 and the differences of the medians and the
trimmed means are 0.5, which are much smaller. The possible cause of thismight
be due to the extreme values (outliers) in the samples, especially the value of 37.
1.6 (a) A dot plot is shown below.
1.95 2.05 2.15 2.25 2.35 2.45 2.55
In the figure, g~h represents the 20.C group and g.h represents the 45.C group.
(b) PX20.C = 2.1075, and PX45.C = 2.2350.
(c) Based on the plot, it seems that high temperature yields more high values of
tensile strength, alongwith a few low values of tensile strength. Overall, the
temperature does have an influence on the tensile strength.
Solutions for Exercises in Chapter 1 3
(d) It also seems that the variation of the tensile strength gets larger when the cure
temperature is increased.
1.7 s2 = 1
15.1 [(3.4.3.787)2+(2.5.3.787)2+(4.8.3.787)2+E E E+(4.8.3.787)2] = 0.94284;
s = ãs2 = ã0.9428 = 0.971.
1.8 s2 =1
20.1 [(18.71 . 20.768)2 + (21.41 . 20.768)2 + E E E + (21.12 . 20.768)2] = 2.5345;
s = ã2.5345 = 1.592.
1.9 s2
No Aging = 1
10.1 [(227 . 222.10)2 + (222 . 222.10)2 + E E E + (221 . 222.10)2] = 42.12;
sNo Aging = ã42.12 = 6.49.
s2
Aging = 1
10.1 [(219 . 209.90)2 + (214 . 209.90)2 + E E E + (205 . 209.90)2] = 23.62;
sAging = ã23.62 = 4.86.
1.10 For company A: s2
A =...