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2023 Fall Semester Exam Review Statistics

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Chapter 1

Question 1
1.

Here is some information about the first 10 U.S. presidents. Identify the individuals and variables in this data set. Classify each variable as categorical or quantitative.

  • Political Party
  • Age at Inauguration
  • State of Birth
  • Name
  • Age at Death
Question 2
2.

The dotplot below displays shows the scores of 21 Statistics students on a 20-point quiz.

What does one dot represent?

Question 3
3.

Question 4
4.

Question 5
5.

Question 6
6.

The dotplots show the total family income of 40 randomly chosen individuals each from Connecticut, Indiana, and Maine, based on U.S. Census data.


Which graph has a higher standard deviation?
ie. Which graph has greater variability?

Question 7
7.

The dotplots show the total family income of 40 randomly chosen individuals each from Connecticut, Indiana, and Maine, based on U.S. Census data.


Which graph has a shape that is closest to being roughly symmetric?

Question 8
8.

The dotplots show the total family income of 40 randomly chosen individuals each from Connecticut, Indiana, and Maine, based on U.S. Census data.


Which graph has the lowest mean?

Chapter 2

Question 9
9.

Question 10
10.

We used technology to compute the mean and median of the distribution.
One is 13 and the other is 14.3.
Based on the histogram from #9, explain how you know which is which without doing any calculations.

Question 11
11.

Using the same histogram from #9, what effect would removing the outliers have on the mean & standard deviation?

Question 12
12.

Find the interquartile range of the data in #9.

Question 13
13.

The standard deviation is 4.05.
Interpret this value in context.

Question 14
14.

The following dotplot gives the sale prices for 40 houses in Ames, Iowa, sold during a recent month. The mean sale price was $203,388 with a standard deviation of $87,609.


Find the percentile of the house that is indicated on the dotplot. Remember percentile means the percent to the LEFT of a value.

Question 15
15.

Question 16
16.

What does a correlation coefficient tell us?

Question 17
17.

How would the correlation value change if the age of crawling was entered in days?

Question 18
18.

Question 19
19.

Using your scatterplot, if the point representing May was removed, how would that affect the equation of the least-squares regression line? Explain.

Question 20
20.

The principal of a high school read a study that reported a positive correlation between the number of calculators owned by high school students and their math achievement. Based on this study, he decides to buy each student at his school 2 calculators, hoping to improve their math achievement.
Explain the flaw in the principal’s reasoning.

Question 21
21.

The scatterplot shows the relationship between latitude and mean July temperature (in degrees Fahrenheit) for 12 cities in the United States.

If you were to predict the mean July temperature in Fairbanks, Alaska, at latitude 65º, how confident would you be in this prediction?

Question 22
22.

Continue with the information from above:
The equation of the regression line relating these variables is

Los Angeles, California, is at latitude 34º and actually has  a mean July temperature of 74º.
Calculate the predicted temperature value for July.
Keep all places past the decimal point, no units.

Question 23
23.

Use the information from above:

Los Angeles, California, is at latitude 34º and actually has a mean July temperature of 74º.

Calculate the residual for the July prediction. Keep all decimal points, no units.

Question 24
24.

Use the information from the regression model:


Interpret the slope of the regression line.

Question 25
25.

Use the information from above:
Does the value of the y intercept have meaning in this context?
If so, interpret the y intercept. If not, explain why.

Question 26
26.

We used a least-squares regression line to model the relationship between x = latitude
and y = mean July temperature (in degrees Fahrenheit) for a sample of 12 cities in the United States. Here is the residual plot for this model.


Explain what the residual plot suggests about the appropriateness of the linear model.

Chapter 3

Question 27
27.

Indicate the following is a valid statistical question. Explain your reasoning.

'How many people visited Acadia National Park last Tuesday?'

Question 28
28.

Indicate if the following is a valid statistical question. Explain your reasoning.

'How many people visit Acadia National Park on a typical weekday in August?'

Question 29
29.

In a recent study of a random sample of 250 U.S. residents, it was found that 85% rated the honesty and ethical standards of nurses as very high or high.

Do you think that the proportion of all U.S. residents who rate the honesty and ethical standards of nurses as very high or high is exactly 0.85? Explain.

Question 30
30.

Question 31
31.

The administration at a high school with 1800 students wants to gather student opinion about parking for students on campus. It isn’t practical to contact all students.

  • Number all students in the school, use a random number generator to draw 50 numbers, survey those corresponding students.
  • Stand at the doors to the courtyard and by the bus drop off and survey students as they enter the school.
  • Send an email to all the students and ask them to fill out the survey online.
  • Voluntary Response Sample
  • Convenience Sample
  • Simple Random Sample (SRS)
Question 32
32.

An opinion poll calls 2000 randomly chosen residential telephone numbers, then asks to speak with an adult member of the household.
The interviewer asks, “Box-office revenues are at an all-time high. How many movies have you watched in a movie theater in the past 12 months?”
In all, 1131 people responded. The researchers used the responses to estimate the mean number of movies adults have watched in a movie theater in the past 12 months.

Categorize the types of bias with the descriptions.

  • Using only residential phone numbers to contact the sample to be surveyed
  • 2000 Randomly chosen phone numbers were called, response from 1131 people were received.
  • Wording of the question could cause people to be more likely to respond favorable
  • Response Bias
  • Undercoverage Bias
Question 33
33.

A recent random sample of n = 805 adult U.S. residents found that the proportion who rated the honesty and ethical standards of nurses as very high or high is 0.85.
This is 0.15 higher than the proportion recorded for doctors, the next highest-ranked profession.

Identify the sample and the population in this setting.

Categorical Variable
Quantitative Variable
The dotplot below displays shows the scores of 21 Statistics students on a 20-point quiz.

a) Describe the shape of the distribution.
b) How does the mean compare to the median?
mean = median
Roughly symmetric
mean < median
mean > median
Skewed left
Skewed right
The dotplot below displays shows the scores of 21 Statistics students on a 20-point quiz.

a) Using the dot plot above, what is the appropriate measure of center and spread?
b) Why would you choose these?
the skew pulls the mean to the right
median & standard deviation
mean & IQR
the skew pulls the mean to the left
the mean & Std Dev are resistant to the skew & outliers, they don't get pulled to the left.
the median & IQR are resistant to the skew & outliers, they don't get pulled to the left.
mean & standard deviation
median & IQR
Do you “binge-watch” television series by viewing multiple episodes of a series at one sitting? A survey of 800 people who “binge-watch” were asked how many episodes is too many to watch in one viewing session.
The results are displayed in the bar chart.


Explain how this graph is misleading.
The scale on the y axis causes the reader to think '5 to 6' is about 10x more frequent than '3 to 4'.
The 'there is no too many' should be listed first since it doesn't include a number.
The graph is not misleading at all.
For a project in their statistics class, Alex and Tempe studied the impact of different types of background music on students’ ability to remember words from a list they were allowed to study for 5 min. Here is a list of how many words one group of students who listened to Beethoven’s Fifth Symphony were able to remember.
11   12   23   15   14   15   14   15
10   14   15   9   11   13   25   11
13   13   12   20   17   23   11   12
12   11   20   20   12   12   19   13
15   10   14   11   7   17   13   18

Use statsmedic.com/applets, 1 quantitative variable. Make a histogram that effectively displays the distribution of words recalled.
Describe the histogram using D.O.F.S.
There are outliers to the left
Roughly symmetric
Range of about 16
Center about 11 or 12
There are no outliers
There are outliers to the right
Center about 15
Range of about 18
Right skewed
Left skewed
The median is 13 and the mean is 14.3 because the outliers pull the mean lower.
At what age do babies learn to crawl? Does it take longer to learn in the winter, when babies are often bundled in clothes that restrict movement? There might even be an association between babies’ crawling age and the average temperature during the month when they first try to crawl (around 6 months after birth).
Data were collected from parents who reported the birth month and the age at which their child was first able to creep or crawl a distance of 4 feet within 1 minute. Information was obtained on 414 infants, 208 boys and 206 girls.
Average crawling age is given in weeks, and the average temperature (in degrees Fahrenheit) is for the month that is 6 months after the birth month.
Copy and paste the data into statsmedic.com/applets, 2 quantitative variables.

Birth Month: Jan. Feb. Mar. Apr. May. Jun. July. Aug. Sept. Oct. Nov. Dec.
Ave. Temp.: 66 73 73 63 52 39 33 30 33 37 48 57
Ave. Age: 29.84 30.52 29.7 31.84 28.58 31.44 33.64 32.82 33.83 33.35 33.38 32.32

Work with a partner, use statsmedic.com to make a scatterplot to display the relationship between average 6-month temperature and average crawling age.

Describe the relationship shown in the scatterplot.
Select all that apply.
If you're not sure of the strength, calculate the correlation.
Negative
Positive
No direction
linear
nonlinear
moderate relationship
strong relationship
weak relationship
Using your scatterplot from above:

a) Describe what is unusual about the point representing May.

b) How does the point representing May affect the equation of the least-squares regression line? Explain.
The point representing May is an outlier, it is outside the pattern of the data.
The point representing May causes the slope to be more negative and
the y-intercept to be lower.
The point representing May is not an outlier, it's not too far out of the pattern of the data.
The point representing May causes the slope to be less negative and
the y-intercept to be higher.
If the point representing May was removed the slope of the regression equation would not change and
If the point representing May was removed the slope of the regression equation would become more negative and
If the point representing May was removed the slope of the regression equation would become less negative and
the y-intercept would become larger.
The calculators caused the students to do better on their math tests and SAT tests showing higher achievement.
Owning a calculator is associated with higher math scores by students.
Owning a calculator causes a students' math scores to improve.
The principal's thinking is flawed because he assumes the calculators caused an improved math achievement.
we would be extrapolating so the calculations would be risky.
Not very confident
For every temperature decrease in degree the latitude goes down 0.782 degrees
it is the latitude when the temperature is zero, at the north pole.
The residual plot shows a strong pattern,
this indicates that the linear model is appropriate.
The residual plot shows random scatter,
the answer does not give varied answers.
it gives answers that are varied.
Yes, the proportion of all U.S. residents who rate the honesty and ethical standards of nurses as very high or high is exactly 0.85.
This cannot be determined without doing a very large randomized study.
due to sampling variability we know 85% is the exact value.
No, the proportion of all U.S. residents who rate the honesty and ethical standards of nurses as very high or high is not exactly 0.85 but it is close.
due to sampling variability we know that 85% is not exact but is close.
Use the previous question information:
If the size of a sample in the poll was increased to 1250 residents, what effect would this have on the variability? Explain.
The variability would increase because
the sample size increased.
The variability would decrease because
the sample size decreased.
The variability would not change because
the sample size did not change.
Nonresponse Bias
the sample is U.S. residents.
The population is all U.S. residents and
the sample is 0.85 U.S. residents.
the sample is 805 adult U.S. residents.
The population is 805 U.S. residents and