Question 1

Autos Hoping to improve the gas mileage of their cars, a car company has made an
adjustment in the manufacturing process. Random samples of automobiles coming off the
assembly line have been measured each week that the plant has been in operation. The
data from before and after the manufacturing adjustments were made are in the table. It is
believed that measurements of gas mileage are normally distributed. Write a complete
conclusion about the manufacturing adjustments based on the statistical software printout
shown below.

Accepted Answer

<img  loading="lazy" src="/assets/images/blured-textbook.svg" class="d-inline m-1" alt="blured image" width="139" height="30"> is strong evidence that the gas mileage...

Question 2

An elementary school principal wants to know the mean number of children in families whose
Children attend this school. He checks all the families using the school's registration records, and we
Create a 95% confidence interval based on a t-distribution. This procedure was not appropriate.
Why?

Accepted Answer

A)   Since these families are from only one school, the family sizes may be skewed.
B)   At a given school families are not randomly selected.
C)   The entire population of families was gathered so there is no reason to do inference.
D)   The recent record-setting family with twelve children is probably an outlier.
E)   The population standard deviation is known, so he should have used a z-model.

Question 3

Cloning A random sample of 800 adults was asked the following question: "Do you think
current laws concerning the use of cloning for medical research are too strict, too lenient, or about
right?" The pollsters also classified the respondents with respect to highest education level
attained: high school, 2- year college degree, 4-year degree, or advanced degree. We wish
to know if attitudes on cloning are related to education level. (All the conditions are
satisfied - don't worry about checking them.)  
a. Write appropriate hypotheses.
b. Suppose the expected counts had not been given. Show how to calculate the expected
count in the first cell (106.01).
c. How many degrees of freedom? Explain.
d. State your complete conclusion in context.

Accepted Answer

a. <img  loading="lazy" src="/assets/images/blured-textbook.svg" class="d-inline m-1" alt="blured image" width="139" height="30"> : People's opinions on cloning are i...

Question 4

Most people are definitely dominant on one side of their body - either right or left. For some sports being able to use both
sides is an advantage, such as batting in baseball or softball. In order to determine if there is a difference in strength between
the dominant and nondominant sides, a few switch-hitting members of some school baseball and softball teams were asked
to hit from both sides of the plate during batting practice. The longest hit (in feet) from each side was recorded for each
player. The data are shown in the table below. $$\begin{array} { | c | c | c | } 
\hline \text { Batter } & \begin{array} { c } 
\text { Dominant } \
\text { Side }
\end{array} & \begin{array} { c } 
\text { Non-dominant } \
\text { Side }
\end{array} \
\hline 1 & 142 & 119 \
\hline 2 & 144 & 118 \
\hline 3 & 153 & 126 \
\hline 4 & 148 & 119 \
\hline 5 & 146 & 121 \
\hline 6 & 149 & 125 \
\hline 7 & 138 & 116 \
\hline 8 & 145 & 120 \
\hline 9 & 153 & 124 \
\hline 10 & 160 & 138 \
\hline 11 & 163 & 135 \
\hline 12 & 170 & 144 \
\hline 13 & 169 & 142 \
\hline 14 & 151 & 128 \
\hline 15 & 152 & 131 \
\hline 16 & 167 & 141 \
\hline 17 & 164 & 140 \
\hline 18 & 165 & 140 \
\hline 19 & 163 & 138 \
\hline
\end{array}$$
-Create and interpret a 95% confidence interval.

Accepted Answer

Under these conditions the sampling dist...

Question 5

Which statement correctly compares t-distributions to the Normal distribution?
I. t distributions are also mound shaped and symmetric.
II. t distributions are more spread out than the normal distribution.
III. As degrees of freedom increase, the variance of t distributions becomes larger.

Accepted Answer

A)   II only
B)   I, II, and III
C)   I only
D)   I and II only
E)   I and III only

Question 6

Could eye color be a warning signal for hearing loss in patients suffering from meningitis?
British researcher Helen Cullington recorded the eye color of 130 deaf patients, and noted
whether the patient's deafness had developed following treatment for meningitis. Her data
are summarized in the table below. Test an appropriate hypothesis and state your
conclusion.

Accepted Answer

<img  loading="lazy" src="/assets/images/blured-textbook.svg" class="d-inline m-1" alt="blured image" width="139" height="30"> : Deafness and eye color are independen...

Question 7

We want to know the mean winning score at the US Open golf championship. An internet search
Gives us all the scores for the history of that tournament, and we create a 95% confidence interval
Based on a t-distribution. This procedure was not appropriate. Why?

Accepted Answer

A)   The population standard deviation is known, so we should have used a z-model.
B)   Since these are the best players in the world, the scores are probably skewed.
C)   The entire population of scores was gathered so there is no reason to do inference.
D)   In big golf tournaments the players are not randomly selected.
E)   The recent record-setting score is probably an outlier.

Question 8

Poverty In a study of how the burden of poverty varies among U. S. regions, a random
sample of 1000 individuals from each region of the United States recently yielded the
information on poverty (based on defining the poverty level as an income below $10,400
for a family of 4 people). The data and calculation of the test statistic is shown in the table
below. (All the conditions are satisfied - don'ft worry about checking them.)  
a. Write appropriate hypotheses.
b. Suppose the expected values had not been given. Show exactly how to calculate the
expected count in the first cell.
c. How many degrees of freedom are there?
d. State your complete conclusion in context.

Accepted Answer

a. <img  loading="lazy" src="/assets/images/blured-textbook.svg" class="d-inline m-1" alt="blured image" width="139" height="30"> : Poverty is independent of geograph...

Question 9

A wildlife biologist wants to determine the mean weight of adult red squirrels. She captures 10
Squirrels she believes to be representative of the species and weighs them, finding a mean of 12.32
Grams and standard deviation of 1.88 gm. Assuming these squirrels can be considered a random
Sample of all red squirrels which of the following formulas gives a 95% confidence interval for the
Mean weight of all squirrels?

Accepted Answer

A)    12.32±1.96(1.88/10) 12.32 \pm 1.96 ( 1.88 / \sqrt { 10 } ) 12.32±1.96(1.88/10c-2.7,0,-7.17,-2.7,-13.5,-8c-5.8,-5.3,-9.5,-10,-9.5,-14c0,-2,0.3,-3.3,1,-4c1.3,-2.7,23.83,-20.7,67.5,-54c44.2,-33.3,65.8,-50.3,66.5,-51c1.3,-1.3,3,-2,5,-2c4.7,0,8.7,3.3,12,10s173,378,173,378c0.7,0,35.3,-71,104,-213c68.7,-142,137.5,-285,206.5,-429c69,-144,104.5,-217.7,106.5,-221l0 -0c5.3,-9.3,12,-14,20,-14H400000v40H845.2724s-225.272,467,-225.272,467s-235,486,-235,486c-2.7,4.7,-9,7,-19,7c-6,0,-10,-1,-12,-3s-194,-422,-194,-422s-65,47,-65,47zM834 80h400000v40h-400000z'/>​)  
B)    12.32±2.262(1.88/10) 12.32 \pm 2.262 ( 1.88 / \sqrt { 10 } ) 12.32±2.262(1.88/10c-2.7,0,-7.17,-2.7,-13.5,-8c-5.8,-5.3,-9.5,-10,-9.5,-14c0,-2,0.3,-3.3,1,-4c1.3,-2.7,23.83,-20.7,67.5,-54c44.2,-33.3,65.8,-50.3,66.5,-51c1.3,-1.3,3,-2,5,-2c4.7,0,8.7,3.3,12,10s173,378,173,378c0.7,0,35.3,-71,104,-213c68.7,-142,137.5,-285,206.5,-429c69,-144,104.5,-217.7,106.5,-221l0 -0c5.3,-9.3,12,-14,20,-14H400000v40H845.2724s-225.272,467,-225.272,467s-235,486,-235,486c-2.7,4.7,-9,7,-19,7c-6,0,-10,-1,-12,-3s-194,-422,-194,-422s-65,47,-65,47zM834 80h400000v40h-400000z'/>​)  
C)    12.32±2.228(1.88/10) 12.32 \pm 2.228 ( 1.88 / \sqrt { 10 } ) 12.32±2.228(1.88/10c-2.7,0,-7.17,-2.7,-13.5,-8c-5.8,-5.3,-9.5,-10,-9.5,-14c0,-2,0.3,-3.3,1,-4c1.3,-2.7,23.83,-20.7,67.5,-54c44.2,-33.3,65.8,-50.3,66.5,-51c1.3,-1.3,3,-2,5,-2c4.7,0,8.7,3.3,12,10s173,378,173,378c0.7,0,35.3,-71,104,-213c68.7,-142,137.5,-285,206.5,-429c69,-144,104.5,-217.7,106.5,-221l0 -0c5.3,-9.3,12,-14,20,-14H400000v40H845.2724s-225.272,467,-225.272,467s-235,486,-235,486c-2.7,4.7,-9,7,-19,7c-6,0,-10,-1,-12,-3s-194,-422,-194,-422s-65,47,-65,47zM834 80h400000v40h-400000z'/>​)  
D)    12.32±2.268(1.88/9) 12.32 \pm 2.268 ( 1.88 / \sqrt { 9 } ) 12.32±2.268(1.88/9c-2.7,0,-7.17,-2.7,-13.5,-8c-5.8,-5.3,-9.5,-10,-9.5,-14c0,-2,0.3,-3.3,1,-4c1.3,-2.7,23.83,-20.7,67.5,-54c44.2,-33.3,65.8,-50.3,66.5,-51c1.3,-1.3,3,-2,5,-2c4.7,0,8.7,3.3,12,10s173,378,173,378c0.7,0,35.3,-71,104,-213c68.7,-142,137.5,-285,206.5,-429c69,-144,104.5,-217.7,106.5,-221l0 -0c5.3,-9.3,12,-14,20,-14H400000v40H845.2724s-225.272,467,-225.272,467s-235,486,-235,486c-2.7,4.7,-9,7,-19,7c-6,0,-10,-1,-12,-3s-194,-422,-194,-422s-65,47,-65,47zM834 80h400000v40h-400000z'/>​)  
E)    12.32±2.228(1.88/9) 12.32 \pm 2.228 ( 1.88 / \sqrt { 9 } ) 12.32±2.228(1.88/9c-2.7,0,-7.17,-2.7,-13.5,-8c-5.8,-5.3,-9.5,-10,-9.5,-14c0,-2,0.3,-3.3,1,-4c1.3,-2.7,23.83,-20.7,67.5,-54c44.2,-33.3,65.8,-50.3,66.5,-51c1.3,-1.3,3,-2,5,-2c4.7,0,8.7,3.3,12,10s173,378,173,378c0.7,0,35.3,-71,104,-213c68.7,-142,137.5,-285,206.5,-429c69,-144,104.5,-217.7,106.5,-221l0 -0c5.3,-9.3,12,-14,20,-14H400000v40H845.2724s-225.272,467,-225.272,467s-235,486,-235,486c-2.7,4.7,-9,7,-19,7c-6,0,-10,-1,-12,-3s-194,-422,-194,-422s-65,47,-65,47zM834 80h400000v40h-400000z'/>​)

Question 10

Which statement correctly compares t-distributions to the normal distribution?
I. t distributions are also mound shaped and symmetric.
II. t distributions have less spread than the normal distribution.
III. As degrees of freedom increase, the variance of t distributions becomes smaller.

Accepted Answer

A)   I, II, and III
B)   I only
C)   I and III only
D)   I and II only
E)   II only

Question 11

One common method of evaluating the performance of a mutual fund is to compare its returns to those of a recognized
benchmark such as an index of the returns on all securities of the type that the fund accumulates. The Janus Worldwide Fund
considers its benchmark to be the MSCI World IndexSM. The table below depicts the annual returns (percent) for a recent
ten-year period. Is this fund a good investment? That is, does this fund significantly outperform its benchmark?  Source:
https://ww3.janus.com/advisor/Documents/Advisor%20Lit%20System/Fact%20Sheets/4Q12%20Fact%20Sheet%20(Janus%20Worldw
ide%20Fund-Class%20A)_exp%2004-15-13.pdf
-Explain clearly whether this data should be analyzed using a 2-sample t test approach or a
match pairs t-test method.

Accepted Answer

This analysis should be conducted as a m...

Question 12

A random sample of 120 college seniors found that 30% of them had been offered jobs. What is the
Standard error of the sample proportion?

Accepted Answer

A)   0.042
B)   0.028
C)   0.458
D)   0.082
E)   0.046

Question 13

Before you took this course, you probably heard many stories about Statistics courses. Oftentimes parents of students have
had bad experiences with Statistics courses and pass on their anxieties to their children. To test whether actually taking
Statistics decreases students' anxieties about Statistics, a Statistics instructor gave a test to rate student anxiety at the
beginning and end of his course. Anxiety levels were measured on a scale of 0-10. Here are the data for 16 randomly chosen
students from a class of 180 students: $$\begin{array} { | l | c | c | c | c | c | c | c | c | c | c | c | c | c | c | c | c | } 
\hline \text { Pre-course anxiety level } & 7 & 6 & 9 & 5 & 6 & 7 & 5 & 7 & 6 & 4 & 3 & 2 & 1 & 3 & 4 & 2 \
\hline \text { Post-course anxiety level } & 4 & 3 & 7 & 3 & 4 & 5 & 4 & 6 & 5 & 3 & 2 & 2 & 1 & 3 & 4 & 3 \
\hline \text { Difference (Post - Pre) } & - 3 & - 3 & - 2 & - 2 & - 2 & - 2 & - 1 & - 1 & - 1 & - 1 & - 1 & 0 & 0 & 0 & 0 & 1 \
\hline
\end{array}$$
-Do the data indicate that anxiety levels about Statistics decreases after students take
Statistics? Test an appropriate hypothesis and state your conclusion.

Accepted Answer

Let <img  loading="lazy" src="/assets/images/blured-textbook.svg" class="d-inline m-1" alt="blured image" width="139" height="30"> Post-course anxiety level - Pre-cou...

Exam 6: Accessing Associations Between Variables

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a. : Poverty is independent of geograph...
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Which statement correctly compares t-distributions to the Normal distribution? I. t distributions are also mound shaped and symmetric. II. t distributions are more spread out than the normal distribution. III. As degrees of freedom increase, the variance of t distributions becomes larger.

Correct Answer
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A random sample of 120 college seniors found that 30% of them had been offered jobs. What is the Standard error of the sample proportion?

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Under these conditions the sampling dist...
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a. : People's opinions on cloning are i...
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is strong evidence that the gas mileage...
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Let Post-course anxiety level - Pre-cou...
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Which statement correctly compares t-distributions to the normal distribution? I. t distributions are also mound shaped and symmetric. II. t distributions have less spread than the normal distribution. III. As degrees of freedom increase, the variance of t distributions becomes smaller.

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Correct Answer
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This analysis should be conducted as a m...
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Correct Answer
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: Deafness and eye color are independen...
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We want to know the mean winning score at the US Open golf championship. An internet search Gives us all the scores for the history of that tournament, and we create a 95% confidence interval Based on a t-distribution. This procedure was not appropriate. Why?

Correct Answer
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Correct Answer
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An elementary school principal wants to know the mean number of children in families whose Children attend this school. He checks all the families using the school's registration records, and we Create a 95% confidence interval based on a t-distribution. This procedure was not appropriate. Why?

Correct Answer
verified

Exam 6: Accessing Associations Between Variables

Correct Answerverifieda. : Poverty is independent of geograph...View AnswerShow Answer

Which statement correctly compares t-distributions to the Normal distribution? I. t distributions are also mound shaped and symmetric. II. t distributions are more spread out than the normal distribution. III. As degrees of freedom increase, the variance of t distributions becomes larger.

Correct AnswerverifiedShow Answer

A random sample of 120 college seniors found that 30% of them had been offered jobs. What is the Standard error of the sample proportion?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedUnder these conditions the sampling dist...View AnswerShow Answer

Correct Answerverifieda. : People's opinions on cloning are i...View AnswerShow Answer

Correct Answerverified is strong evidence that the gas mileage...View AnswerShow Answer

Correct AnswerverifiedLet Post-course anxiety level - Pre-cou...View AnswerShow Answer

Which statement correctly compares t-distributions to the normal distribution? I. t distributions are also mound shaped and symmetric. II. t distributions have less spread than the normal distribution. III. As degrees of freedom increase, the variance of t distributions becomes smaller.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedThis analysis should be conducted as a m...View AnswerShow Answer

Correct Answerverified : Deafness and eye color are independen...View AnswerShow Answer

We want to know the mean winning score at the US Open golf championship. An internet search Gives us all the scores for the history of that tournament, and we create a 95% confidence interval Based on a t-distribution. This procedure was not appropriate. Why?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

An elementary school principal wants to know the mean number of children in families whose Children attend this school. He checks all the families using the school's registration records, and we Create a 95% confidence interval based on a t-distribution. This procedure was not appropriate. Why?

Correct AnswerverifiedShow Answer

Correct Answer
verified
a. : Poverty is independent of geograph...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
Under these conditions the sampling dist...
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Correct Answer
verified
a. : People's opinions on cloning are i...
View Answer

Correct Answer
verified
is strong evidence that the gas mileage...
View Answer

Correct Answer
verified
Let Post-course anxiety level - Pre-cou...
View Answer

Correct Answer
verified

Correct Answer
verified
This analysis should be conducted as a m...
View Answer

Correct Answer
verified
: Deafness and eye color are independen...
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Correct Answer
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Correct Answer
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Correct Answer
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