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Chapter7Homework-MATH1123sectionOBFall2023_WebAssign.pdf
11/17/23, 10:30 PM Chapter 7 Homework - MATH1123, section OB, Fall 2023 | WebAssign
https://www.webassign.net/web/Student/Assignment-Responses/last?dep=33177291 1/9
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MATH1123, section OB, Fall 2023
Chapter 7 Homework (Homework) INSTRUCTOR
Hua He
Hawaii Paci�c University
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11/17/23, 10:30 PM Chapter 7 Homework - MATH1123, section OB, Fall 2023 | WebAssign
https://www.webassign.net/web/Student/Assignment-Responses/last?dep=33177291 2/9
The report "Social Media Use in 2021" summarizes data from a survey of a representative sample of 1,447 adult Americans. The sample included 220 people of age 18 to 29, 798 people of age 30 to 64, and 429 people of age 65 and older. The following statements are based on the survey data.
23% of adult Americans use Twitter 42% of Americans between the ages of 18 and 29 use Twitter 7% of Americans age 65 and older use Twitter.
Are the inferences made ones that involve estimation or ones that involve hypothesis testing? (Hint: See Example 7.1.)
†
The inference made involves estimation.
The inference made involves hypothesis testing.
1. [1/1 Points] PECKSTAT3 7.1.001.DETAILS PREVIOUS ANSWERS MY NOTES
11/17/23, 10:30 PM Chapter 7 Homework - MATH1123, section OB, Fall 2023 | WebAssign
https://www.webassign.net/web/Student/Assignment-Responses/last?dep=33177291 3/9
A report summarizes data from a survey of a representative sample of 1,449 adult Americans. The sample included 221 people of age 18 to 29, 796 people of age 30 to 64, and 432 people of age 65 and older. The following statements are based on the survey data.
23% of adult Americans use Twitter 42% of Americans between the ages of 18 and 29 use Twitter 7% of Americans age 65 and older use Twitter.
(a) What is the population of interest?
all Americans who use Twitter
all Americans
adult Americans
adults who use Twitter
adult Americans who use Twitter
(b) What population characteristics are being estimated?
the percentage of the population of interest who are adults
the total number of people in the population of interest who have used Twitter
the percentage of the population of interest who use Twitter
the total number of people in the population of interest
the percentage of the population of interest who are American
(c) Do you think that the actual percentage of all adult Americans who use Twitter is exactly 23%? Explain why or why not.
Yes. This percentage is a population characteristic, meaning it describes the total population of interest.
No. The size of the sample this estimate was based on is very small.
No. Subsequent samples may yield different estimates for this percentage.
Yes. This estimate was based on a representative sample of the population of interest.
(d) Two of the estimates of population characteristics from this study were that 23% of adult Americans use Twitter and that 42% of Americans between the ages of 18 and 29 use Twitter. Which of these two estimates do you think is more accurate, and why? (Hint: What do you know about the number of people surveyed in each of these two groups?)
The percentage of adult Americans who use twitter was estimated using a sample of size while the
percentage of Americans aged 18 to 29 who use Twitter was estimated using a sample of size . Since the
sample size for adult Americans was ---Select--- that of Americans aged 18 to 29, we should expect ---Select--- .
2. [–/7 Points] PECKSTAT3 7.1.002.DETAILS MY NOTES PRACTICE ANOTHER
11/17/23, 10:30 PM Chapter 7 Homework - MATH1123, section OB, Fall 2023 | WebAssign
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Do people better remember what they learned if they are in the same physical space where they first learned it? The authors of the paper "The Dynamics of Memory: Context-Dependent Updating" asked people to learn a set of 20 unrelated objects. Two days later, these people were asked to recall the objects learned on the first day. Some of the people were asked to recall the objects in the same room where they originally learned the objects. The others were asked to recall the objects in a different room. People were assigned at random to one of these two recall conditions. The authors found that the data on the number of objects recalled supported the claim that recall is better when people return to the original learning context. Is the inference made one that involves estimation or one that involves hypothesis testing?
†
The inference made involves estimation.
The inference made involves hypothesis testing.
3. [1/1 Points] PECKSTAT3 7.1.006.DETAILS PREVIOUS ANSWERS MY NOTES
11/17/23, 10:30 PM Chapter 7 Homework - MATH1123, section OB, Fall 2023 | WebAssign
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The article "The Largest Last Supper: Depictions of Food Portions and Plate Size Increase Over the Millennium" describes a study in which each painting in a sample of 52 paintings of The Last Supper was analyzed by comparing the size of the food plates in the painting to the head sizes of the people in the painting. For paintings that were painted prior to the year 1500, the estimated average plate-to-head size ratio was smaller than this ratio for the paintings that were painted after the year 1500.
(a) The original sample consisted of 52 paintings. These paintings were then divided into two samples consisting of 30 painted before 1500 and 22 painted after 1500. What are the two populations of interest?
The two populations are head size and plate size in paintings of The Last Supper.
The two populations are people born prior to the year 1500, and people born after the year 1500.
The two populations are artists painting prior to the year 1500, and artists painting after the year 1500.
The two populations are paintings of The Last Supper made prior to the year 1500, and paintings of The Last Supper made after the year 1500.
(b) What population characteristics are being estimated?
the plate sizes in paintings of The Last Supper
the head sizes in paintings of The Last Supper
the plate-to-head size ratios in paintings of The Last Supper
the number of paintings of The Last Supper made after the year 1500
the number of paintings of The Last Supper made prior to the year 1500
(c) Suppose that the paintings selected for analysis were selected at random from all paintings that portray The Last Supper. Do you think that the estimate produced for average plate-to-head size ratio for paintings made before 1500 is likely to be less accurate than the corresponding estimate for paintings made after 1500? Explain.
Yes, the estimate of average plate-to-head size ratio would be more accurate for paintings made after 1500 because the sample size is larger.
Yes, the estimate of average plate-to-head size ratio would be more accurate for paintings made after 1500 because the sample size is smaller.
No, the estimate of average plate-to-head size ratio would be more accurate for paintings made before 1500 because the sample size is larger.
No, the estimate of average plate-to-head size ratio would be more accurate for paintings made before 1500 because the sample size is smaller.
†
4. [–/3 Points] PECKSTAT3 7.1.008.DETAILS MY NOTES
11/17/23, 10:30 PM Chapter 7 Homework - MATH1123, section OB, Fall 2023 | WebAssign
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In 2021, the Pew Research Center conducted a survey of a representative sample of 1,502 adults in the U.S. to learn about smartphone ownership and access to broadband. Each person in the sample was asked if they own a smartphone. The resulting data could be used to learn about the proportion of adults in the United States who own a smartphone. (Hint: See Example 7.7.)
Answer the four key questions.
Q, Question Type: Estimation or hypothesis testing?
S, Study Type: Sample data or experiment data?
T, Type of Data: One variable or two? Categorical or numerical?
two categorical variables
two numerical variables
one categorical variable
one numerical variable
N, Number of Samples or Treatments: How many samples or treatments?
one sample
two samples
two treatments
one treatment
†
estimation
hypothesis testing
sample data
experimental data
5. [2/4 Points] PECKSTAT3 7.2.016.DETAILS PREVIOUS ANSWERS MY NOTES
11/17/23, 10:30 PM Chapter 7 Homework - MATH1123, section OB, Fall 2023 | WebAssign
https://www.webassign.net/web/Student/Assignment-Responses/last?dep=33177291 7/9
The article "Smartphone Nation"† describes a study of how people ages 50 to 64 years use cell phones. In this study, each person in a sample of adults thought to be representative of this age group was asked about whether he or she kept a cell phone by the bed at night. The researchers conducting this study hoped to use the resulting data to learn about the proportion of people in this age group who sleep with their cell phone nearby. (Hint: See Example 7.7.)
Answer the four key questions.
Q, Question Type: Estimation or hypothesis testing?
S, Study Type: Sample data or experiment data?
T, Type of Data: One variable or two? Categorical or numerical?
one categorical variable
one numerical variable
two categorical variables
two numerical variables
N, Number of Samples or Treatments: How many samples or treatments?
one sample
one treatment
two samples
two treatments
estimation
hypothesis testing
sample data
experiment data
6. [2/4 Points] PECKSTAT3 7.2.501.XP.DETAILS PREVIOUS ANSWERS MY NOTES
11/17/23, 10:30 PM Chapter 7 Homework - MATH1123, section OB, Fall 2023 | WebAssign
https://www.webassign.net/web/Student/Assignment-Responses/last?dep=33177291 8/9
Is the proportion of childless adults in the United States who don't plan to ever have children increasing over time? This question was investigated using data from two surveys of adults ages 18 to 49 who do not have children, one conducted in 2018 and one conducted in 2021. The data from these two samples were used to estimate the difference in the proportions who don't plan to have children for the two years.
Answer the four key questions.
Q, Question Type: Estimation or hypothesis testing?
S, Study Type: Sample data or experiment data?
T, Type of Data: One variable or two? Categorical or numerical?
two categorical variables
two numerical variables
one numerical variable
one categorical variable
N, Number of Samples or Treatments: How many samples or treatments?
one treatment
one sample
two samples
two treatments
†
estimation
hypothesis testing
sample data
experimental data
7. [2/4 Points] PECKSTAT3 7.2.023.DETAILS PREVIOUS ANSWERS MY NOTES
11/17/23, 10:30 PM Chapter 7 Homework - MATH1123, section OB, Fall 2023 | WebAssign
https://www.webassign.net/web/Student/Assignment-Responses/last?dep=33177291 9/9
Common Sense Media surveyed 1,000 teens and 1,000 parents of teens to learn about how teens are using social networking sites such as Facebook and MySpace.† The two samples were independently selected and were chosen in a way that makes it reasonable to regard them as representative of American teens and parents of American teens. When asked if they check their online social networking sites more than 10 times a day, 220 of the teens surveyed said yes. When parents of teens were asked if their teen checks his or her site more than 10 times a day, 40 said yes. The researchers used these data to conclude that there was evidence that the proportion of all parents who think their teen checks a social networking site more than 10 times a day is less than the proportion of all teens who report that they check the sites more than 10 times a day.
Answer the four key questions.
Q, Question Type: Estimation or hypothesis testing?
S, Study Type: Sample data or experiment data?
T, Type of Data: One variable or two? Categorical or numerical?
one categorical variable
one numerical variable
two categorical variables
two numerical variables
N, Number of Samples or Treatments: How many samples or treatments?
one sample
one treatment
two samples
two treatments
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estimation
hypothesis testing
sample data
experiment data
8. [2/4 Points] PECKSTAT3 7.2.502.XP.DETAILS PREVIOUS ANSWERS MY NOTES
