Question 1

Students taking an intro stats class reported the number of credit hours that they were
taking that quarter. Summary statistics are shown in the table. $$\begin{array} { | l | c | } 
\hline \bar { x } & 16.65 \
\hline s & 2.96 \
\hline \text { min } & 5 \
\hline \text { Q1 } & 15 \
\hline \text { median } & 16 \
\hline \text { Q3 } & 19 \
\hline \text { max } & 28 \
\hline
\end{array}$$ 
a. Suppose that the college charges $73 per credit hour plus a flat student fee of $35 per
quarter. For example, a student taking 12 credit hours would pay $35 $$\$ 35 + \$ 73 ( 12 ) = \$ 911 \text { for }$$ 
that quarter.
i. What is the mean fee paid?
ii. What is the standard deviation for the fees paid?
iii. What is the median fee paid?
iv. What is the IQR for the fees paid?
b. Twenty-eight credit hours seems like a lot. Would you consider 28 credit hours to be
unusually high? Explain.

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Question 2

Compare the two distributions of the women's heights. Be sure to talk about shape, center,
and spread.

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Question 3

a. Sketch a histogram for these data.
b. Find the mean and standard deviation of the roller coaster lengths.
c. Is it appropriate to use the mean and standard deviation to summarize these data?
Explain.
d. Describe the distribution of roller coaster lengths.

Accepted Answer

The answer of a. Sketch a histogram for these data.
b....

Question 4

The five-number summary for midterm scores (number of points; the maximum possible
score was 50 points) from an intro stats class is: $$\begin{array} { | c | c | c | c | c | } 
\hline \text { Min } & \mathrm { Q } 1 & \text { Median } & \text { Q3 } & \text { Max } \
\hline 16.5 & 32 & 39 & 43.5 & 48.5 \
\hline
\end{array}$$ 
a. Would you expect the mean midterm score of all students who took the midterm to be
higher or lower than the median? Explain.
b. Based on the five-number summary, are any of the midterm scores outliers? Explain.

Accepted Answer

The answer of The five-number summary for midterm scores (number...

Question 5

At www.census.gov you can create a "population pyramid" for any country. These
pyramids are back-to-back histograms. This pyramid shows Mexico's 2000 female
population and the census bureau's projection for 2050. Write a few sentences
summarizing the changes that are forecast.

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The answer of At www.census.gov you can create a "population...

Question 6

The boxplots show the age of people involved in accidents according to their role in
the accident.  
a. Which role involved the youngest person, and what is the age?
b. Which role had the lowest median age, and what is the age?
c. Which role had smallest range of ages, and what is it?
d. Which role had the largest IQR of ages, and what is it?
e. Which role generally involves the oldest people? Explain.

Accepted Answer

The answer of The boxplots show the age of people...

Question 7

The boxplots show fuel economy of 2011 model cars for the classes shown.  
a. Which class offers the car with the best gas mileage, and what is the mileage of that car?
b. Which class has the highest median gas mileage, and how much is it?
c. Which class of car has the smallest range of fuel economy, and what is it?
d. Which class of car has the smallest IQR, and what is it?
e. Which class of car generally gets the best mileage? Explain.

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Question 8

The Wechsler Adult Intelligence Scale - Revised (WAIS-R) follows a Normal model with
mean 100 and standard deviation 15. Draw and clearly label this model.

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The answer of The Wechsler Adult Intelligence Scale - Revised...

Question 9

The body temperature of students is taken each time a student goes to the nurse's office.
The five-number summary for the temperatures (in degrees Fahrenheit) of students on a
particular day is: $$\begin{array} { | c | c | c | c | c | } 
\hline \text { Min } & \text { Q1 } & \text { Median } & \text { Q3 } & \text { Max } \
\hline 96.6 ^ { \circ } & 97.85 ^ { \circ } & 98.25 ^ { \circ } & 98.6 ^ { \circ } & 101.8 ^ { \circ } \
\hline
\end{array}$$ 
a. Would you expect the mean temperature of all students who visited the nurse's office to
be higher or lower than the median? Explain.
b. After the data were picked up in the afternoon, three more students visited the nurse's
office with temperatures of 96.7°, 98.4°, and 99.2°. Were any of these students outliers
(according to the original statistics above)? Explain.

Accepted Answer

The answer of The body temperature of students is taken...

Question 10

One thousand students from a local university were sampled to gather information such as
gender, high school GPA, college GPA, and total SAT scores. The results were used to
create histograms displaying high school grade point averages (GPAs) for both males and
females. Compare the grade distribution of males and females.

Accepted Answer

The answer of One thousand students from a local university...

Question 11

The five-number summary for the fuel economy (in miles per gallon) of year 2011 midsize
cars is: $$\begin{array} { | c | c | c | c | c | } 
\hline \text { Min } & \text { Q1 } & \text { Median } & \text { Q3 } & \text { Max } \
\hline 13 & 21 & 23 & 26 & 50 \
\hline
\end{array}$$ 
a. Would you expect the mean gas mileage of all midsize cars to be higher or lower than
the median? Explain.
b. One model of Volkswagon gets 34 mpg, one model of Toyota gets 28 mpg, and one
model of Bentley gets 13 mpg. Are any of these cars outliers (according to the original
statistics above)? Explain.

Accepted Answer

The answer of The five-number summary for the fuel economy...

Question 12

How do sports salaries compare? Two sets of histograms below show the distributions of
salaries for Major League Baseball and the National Football League. Give two reasons
why the second set of histograms makes it easier to compare the distributions. Then write a
few sentences comparing the salary distributions for the two sports.

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The answer of How do sports salaries compare? Two sets...

Question 13

All students in a physical education class completed a basketball free-throw shooting
event and the highest number of shots made was 32. The next day a student who had just
transferred into the school completed the event, making 35 shots. Indicate whether adding
the new student's score to the rest of the data made each of these summary statistics
increase, decrease, or stay about the same:
a. mean
b. median
c. range
d. IQR
e. standard deviation

Accepted Answer

The answer of All students in a physical education class...

Question 14

The boxplots show prices of used cars (in thousands of dollars) advertised for sale at three
different car dealers.  
a. Which dealer offers the cheapest car offered, and at what price?
b. Which dealer has the lowest median price, and how much is it?
c. Which dealer has the smallest price range, and what is it?
d. Which dealer's prices have the smallest IQR, and what is it?
e. Which dealer generally sells cars cheapest? Explain.

Accepted Answer

The answer of The boxplots show prices of used cars...

Question 15

On Monday, a class of students took a big test, and the highest score was 92. The next day,
a student who had been absent made up the test, scoring 100. Indicate whether adding that
student's score to the rest of the data made each of these summary statistics increase,
decrease, or stay about the same:
a. mean
b. median
c. range
d. IQR
e. standard deviation

Accepted Answer

The answer of On Monday, a class of students took...

Question 16

The five-number summary for the weights (in pounds) of fish caught in a bass tournament
is: $$\begin{array} { | c | c | c | c | c | } 
\hline \text { Min } & \text { Q1 } & \text { Median } & \text { Q3 } & \text { Max } \
\hline 2.3 & 2.8 & 3.0 & 3.3 & 4.5 \
\hline
\end{array}$$ 
a. Would you expect the mean weight of all fish caught to be higher or lower than the
median? Explain.
b. You caught 3 bass weighing 2.3 pounds, 3.9 pounds, and 4.2 pounds. Were any of your
fish outliers (according to the original statistics above)? Explain.

Accepted Answer

The answer of The five-number summary for the weights (in...

Question 17

The side-by-side boxplots show the cumulative college GPAs for sophomores, juniors, and
seniors taking an intro stats course in Autumn 2003.  
a. Which class (sophomore, junior, or senior) had the lowest cumulative college GPA?
What is the approximate value of that GPA?
b. Which class has the highest median GPA, and what is that GPA?
c. Which class has the largest range for GPA, and what is it?
d. Which class has the most symmetric set of GPAs? The most skewed set of GPAs?

Accepted Answer

The answer of The side-by-side boxplots show the cumulative college...

Question 18

There is a proposal to replace the shortest roller coaster above with one that has a length of
1,200 ft. Indicate whether changing that roller coaster's length would make each of these
summary statistics increase, decrease, or stay about the same.
a. mean
b. median
c. range
d. IQR
e. standard deviation

Accepted Answer

The answer of There is a proposal to replace the...

Question 19

While the scales of the histograms are the same, there is something that could be improved
so that we could compare these two distributions better. Identify this improvement and
explain why it would be better.

Accepted Answer

The answer of While the scales of the histograms are...

Question 20

A brake and muffler shop reported the repair bills, in dollars, for their customers
yesterday. $$\begin{array} { | l | l | l | l | l | } 
\hline 88 & 283 & 312 & 290 & 172 \
\hline 154 & 400 & 381 & 346 & 181 \
\hline 203 & 118 & 143 & 252 & 227 \
\hline 56 & 192 & 292 & 213 & 422 \
\hline
\end{array}$$ 
a. Sketch a histogram for these data.
b. Find the mean and standard deviation of the repair costs.
c. Is it appropriate to use the mean and standard deviation to summarize these data?
Explain.
d. Describe the association of repair costs.

Accepted Answer

The answer of A brake and muffler shop reported the...

Quiz 8: Regression, Associations, and Predictive Modeling

Compare the two distributions of the women's heights. Be sure to talk about shape, center, and spread.

a. Sketch a histogram for these data. b. Find the mean and standard deviation of the roller coaster lengths. c. Is it appropriate to use the mean and standard deviation to summarize these data? Explain. d. Describe the distribution of roller coaster lengths.

At www.census.gov you can create a "population pyramid" for any country. These pyramids are back-to-back histograms. This pyramid shows Mexico's 2000 female population and the census bureau's projection for 2050. Write a few sentences summarizing the changes that are forecast.

The Wechsler Adult Intelligence Scale - Revised (WAIS-R) follows a Normal model with mean 100 and standard deviation 15. Draw and clearly label this model.

While the scales of the histograms are the same, there is something that could be improved so that we could compare these two distributions better. Identify this improvement and explain why it would be better.