PROBABILITY & STATISTICS FOR ENGINEERS & SCIENTISTS EIGHTH
09/03/2025
EDITION
Solution manuals_
PROBABILITY & STATISTICS FOR ENGINEERS & SCIENTISTS 8th EDITION
(WALPOLE, MYERS, MYERS, YE)All chapters 1-18 (solved questions) latest 2025
T T
E E
S S
T T
B B
A A
N N
K K
, PROBABILITY & STATISTICS FOR ENGINEERS & SCIENTISTS EIGHTH
09/03/2025
EDITION
Chapter 1
Introduction to Statistics and Data Analysis
1.1 (a) 15.
(b) x̄ = 1 (3.4 +
15 2.5 + 4.8 + · · · + 4.8) = 3.787.
(c) Sample median is the 8th value, after the data is sorted from smallest to 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
1
x̄ tr20 = (2.9 + 3.0 + · · · + 4.8) = 3.678.
9
1.2 (a) Mean=20.768 and Median=20.610.
(b) x̄ tr10 = 20.743.
(c) A dot plot is shown below.
18 19 20 21 22 23
1
,
, 1.3 (a) A dot plot is shown below.
200 205 210 215 220 225 230
In the figure, “ ×” represents the “No aging” group and “ ◦” represents the “Aging”
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) X̄ A = 7.950 and X̃ A = 8.250;
X̄ B = 10.260 and X̃ B = 10.150.
(b) A dot plot is shown below.
6.5 7.5 8.5 9.5 10.5 11.5
In the figure, “×” represents company A and “◦” 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
In the figure, “ ×” represents the control group and “ ”◦ represents the treatment
group.
(b) X̄Control = 5.60, X̃ Control = 5.00, and X̄tr(10);Control = 5.13;
X̄Treatment = 7.60, X̃Treatment = 4.50, and X̄tr(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 this might 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, “×” represents the 20◦C group and “◦” represents the 45◦C group.
(b) X̄ 2 0 ◦ C = 2.1075, and X̄ 45 ◦ C = 2.2350.
(c) Based on the plot, it seems that high temperature yields more high values of
tensile strength, along with a few low values of tensile strength. Overall, the
temperature does have an influence on the tensile strength.
09/03/2025
EDITION
Solution manuals_
PROBABILITY & STATISTICS FOR ENGINEERS & SCIENTISTS 8th EDITION
(WALPOLE, MYERS, MYERS, YE)All chapters 1-18 (solved questions) latest 2025
T T
E E
S S
T T
B B
A A
N N
K K
, PROBABILITY & STATISTICS FOR ENGINEERS & SCIENTISTS EIGHTH
09/03/2025
EDITION
Chapter 1
Introduction to Statistics and Data Analysis
1.1 (a) 15.
(b) x̄ = 1 (3.4 +
15 2.5 + 4.8 + · · · + 4.8) = 3.787.
(c) Sample median is the 8th value, after the data is sorted from smallest to 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
1
x̄ tr20 = (2.9 + 3.0 + · · · + 4.8) = 3.678.
9
1.2 (a) Mean=20.768 and Median=20.610.
(b) x̄ tr10 = 20.743.
(c) A dot plot is shown below.
18 19 20 21 22 23
1
,
, 1.3 (a) A dot plot is shown below.
200 205 210 215 220 225 230
In the figure, “ ×” represents the “No aging” group and “ ◦” represents the “Aging”
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) X̄ A = 7.950 and X̃ A = 8.250;
X̄ B = 10.260 and X̃ B = 10.150.
(b) A dot plot is shown below.
6.5 7.5 8.5 9.5 10.5 11.5
In the figure, “×” represents company A and “◦” 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
In the figure, “ ×” represents the control group and “ ”◦ represents the treatment
group.
(b) X̄Control = 5.60, X̃ Control = 5.00, and X̄tr(10);Control = 5.13;
X̄Treatment = 7.60, X̃Treatment = 4.50, and X̄tr(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 this might 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, “×” represents the 20◦C group and “◦” represents the 45◦C group.
(b) X̄ 2 0 ◦ C = 2.1075, and X̄ 45 ◦ C = 2.2350.
(c) Based on the plot, it seems that high temperature yields more high values of
tensile strength, along with a few low values of tensile strength. Overall, the
temperature does have an influence on the tensile strength.
