Informal Writing Assignment: Perceptions, Attitudes, Understanding and Feelings

Assignment details: This writing assignment requires you to give an honest assessment of your perceptions, attitudes, and feelings about statistics. Your paper should be formatted as introduction, paragraphs, and conclusion. The length of the paper must be at least 1 full page that address the following questions:

1. Discuss your attitudes and feelings about taking statistics. Use one of the following frames to start writing your perceptions of statistics.
2. Statistics is…
3. Taking a statistics class make me feel…

• In order to reduce my anxiety about taking statistics I will…

2. What are your major (Communication: Mass Media) concerns about taking a course in statistics?

3. Discuss your personal objective for this course and discuss in detail the steps you will take to achieve these objectives.

4. What do know about Statistics form your K-12 Education?

5. How does Statistics play a role to your major?

Grading: I will judge the essay on the following criteria:

• Style, clarity, and mechanics of writing

STAT200 – Final Exam
200 points – Due: Tuesday, December 15th.
Please provide a complete response to each item. Include a sketch, calculations,
rationale written using proper statistical language, and any conclusions drawn from the
context of the problem, as necessary.
1. Determine whether the discrete random variable is discrete or continuous. In
each case, state the possible values of the random variable.
a. The number of students in a randomly selected third-grade classroom.
b. The amount of snow that falls in Delaware during the winter season.
c. The flight time accrued by a randomly selected Air Force fighter pilot.
d. The number of points scored by the Duke Blue Devils during a randomly
selected basketball game.
2. The number of chocolate chips in an 18-ounce bag of Chips Ahoy! chocolate chips
is approximately normally distributed with a mean of 1262 chips and a standard
deviation of 118 chips according to a study by cadets in the U.S. Air Force
Academy.
a. What is the probability that a randomly selected 18-ounce bag of Chips
Ahoy! contains between 1100 and 1300 chocolate chips, inclusive?
b. What proportion of 18-ounce bag of Chips Ahoy! contains fewer than 1125
chips?
c. What is the percentile rank of an 18-ounce bag of Chips Ahoy! that
contains 1350 chocolate chips?
STAT200: F2/20 – MDonovan 1
3. The General Social Survey asked: “How many emails do you send in a day?” The
results of 928 respondents indicate that the mean number of emails sent in a day
is 10.4 with a standard deviation of 28.5.
a. Given the fact that 1 standard deviation to the left of the mean results in a
negative number of emails being sent, what shape would you expect the
distribution of emails sent to have?
b. Construct and interpret a 90% confidence interval for the mean number of
emails sent per day.
4. Man-ly Muscles? Young men in North America and Europe (but not in Asia) tend
to think they need more muscle to be attractive. One study presented 200 young
American men with 100 images of men with various levels of muscle.
Researchers measured the level of muscle in kilograms per square meter (kg/m2)
of fat-free body mass. Typical young men have about 20 kg/m2
. Each subject
chose two images, one that represented his own level of body muscle, and one he
thought represented “what women prefer.” The mean gap between self-image
and “what women prefer” was 2.35 kg/m2
.
Suppose that the “muscle gap” in the population of all young men has a Normal
distribution with a standard deviation of 2.5 kg/m2
. Give a 90% confidence
interval for the mean amount of muscle young men think they should have to be
attractive to women.
Note: A second study was done surveying women, it showed women actually prefer a level close to that of a ”typical man”.
5. More Muscle? If young men thought that their own level of muscle was about
what women prefer, the mean “muscle gap”, discussed in a previous exercise,
would be 0. We suspect (before seeing the data) that young men think women
prefer more muscles than they themselves have.
a. State the null and alternative hypotheses for testing this suspicion.
b. What is the value of the test statistic z ?
c. State a complete conclusion.
STAT200: F2/20 – MDonovan 2
6. According to the Centers for Disease Control and Prevention, 16.8% of high
school students currently use electronic cigarettes. A high school counselor is
concerned that the use of e-cigs at his school is actually higher.
a. Determine the null and alternative hypotheses.
b. If the sample data indicate that the null hypothesis should not be rejected,
state the conclusion of the school counselor.
.
7. In December 2005, 38% of adults with children under the age of 18 reported that
their family ate dinner together seven nights a week. In a recent poll, 503 of 1232
adults with children under the age of 18 reported that their family ate dinner
together seven nights a week. Has the proportion of families with children under
the ages of 18 who eat dinner together seven nights a week increased? Test at the
0.05 significance level.
8. Researchers at Harris Interactive wondered if there was a difference between
males and females in regard to some common annoyances. They asked a random
sample of males and females, the following question:
“Are you annoyed by people who repeatedly check their mobile phones while
having an in-person conversation?”
● Among the 540 males surveyed, 178 responded “Yes”
● Among the 560 females surveyed, 206 responded “Yes”
a. Does the evidence suggest a higher proportion of females are annoyed by
this behavior? State the null and alternative hypotheses?
b. Determine and interpret the p-value.
c. At the 0.05 level of significance, what is the conclusion of the hypothesis
test?
STAT200: F2/20 – MDonovan 3
9. A researcher for the U.S. Department of Treasury wishes to estimate the
percentage of Americans who support abolishing the penny. What size sample
should be obtained if she wishes the estimate to be within 2 percentage points
with 98% confidence level, if:
a. she uses a 2006 estimate of 28% obtained from a Coinstar National
Currency Poll?
b. she does not use any prior estimate?
10. The following data represent the number of days absent from class, x, and the
final grade, y, for a sample of college students grade in an introductory statistics
course at a large state university.
a. Find the least-squares regression line treating the number of absences as
the explanatory variable and final grade as the response variable.
b. Interpret the slope and y-intercept, as appropriate.
c. Predict the final grade for a student who misses five class periods and
compute the residual. Is the final grade above or below average for this
number of absences?

STAT 200 Week 7 Homework Problems
10.1.1
Does education pay? The scatter diagram drawn in MiniTab shows the relation between the percentage of the population of a state plus Washington, DC, that has at least a bachelor’s degree and the median income (in dollars) of the state for 2013. Source: U.S. Census Bureau
 
 
 
 
 
Describe any relation that appears to exist between the level of education and median income.
One observation appears to stick out from the rest. Which one? This particular observation is for Washington, DC. Can you think of any reasons why DC, outlies the other states?
The correlation coefficient between the percentage of the population with a bachelor’s degree and median income is 0.854. Does a linear relation exist between percent of the population with at least a bachelor’s degree and median income?
10.1.2
Education and Birthrate. The following scatter diagram drawn in Excel shows the relation between the percent of the population with at least a bachelors degree in a state and birthrate (births per 1000 women 15 to 44 years old).
 
 
 
 
 
Describe any relation that exists between median income and birthrate.
The correlation between percent of population with at least a bachelor’s degree and birth rate is -0.069. What does this imply about the relation between median income and birthrate?
10.1.3
In Problem 10.1.1, a scatter diagram and correlation coefficient suggested there is a linear relationship between the percentage of individuals who have at least a bachelor’s degree and median income in the states. In fact, the least-squares regression equation is where y is the median income and x is the percentage of individuals 25 years and older with at least a bachelor’s degree in the state.
Predict the median income of a state in which 25% of adults 25 years and older have at least a bachelor’s degree.
In North Dakota, 27.1 percent of adults have at least a bachelor’s degree. The median income in North Dakota is $37,193. Is this income higher than what you would expect? Why?
Interpret the slope.
Explain why it does not make sense to interpret the intercept.
10.1.4
Table #1 contains the value of the house and the amount of rental income in a year that the house brings in (“Capital and rental,” 2013). Create a scatter plot and find a regression equation between house value and rental income. Then use the regression equation to find the rental income a house worth $230,000 and for a house worth $400,000. Which rental income that you calculated do you think is closer to the true rental income? Why?
Table #1: Data of House Value versus Rental
 
 
10.1.5
An engineer wants to determine how the weight of a car, x, affects gas milage, y. The following data represents the weights of various domestic cars and their miles per gallon in the city for the 2018 model year.
 
 
 
 
 
Find the least-squares regression line treating weight as the explanatory variable and miles per gallon as the response variable.
Interpret the slope and y-intercept, if appropriate.
A Cadillac CTS weighs 3649 pounds and gets 20 miles per gallon. Is the miles per gallon of a CTS above average or below average for this weight?
Would it be reasonable to use the least-squares regression line to predict the miles per gallon of a Toyota Prius, a hybrid gas and electric car? Why or why not?