New Semester
Started
Get
50% OFF
Study Help!
--h --m --s
Claim Now
Question Answers
Textbooks
Find textbooks, questions and answers
Oops, something went wrong!
Change your search query and then try again
S
Books
FREE
Study Help
Expert Questions
Accounting
General Management
Mathematics
Finance
Organizational Behaviour
Law
Physics
Operating System
Management Leadership
Sociology
Programming
Marketing
Database
Computer Network
Economics
Textbooks Solutions
Accounting
Managerial Accounting
Management Leadership
Cost Accounting
Statistics
Business Law
Corporate Finance
Finance
Economics
Auditing
Tutors
Online Tutors
Find a Tutor
Hire a Tutor
Become a Tutor
AI Tutor
AI Study Planner
NEW
Sell Books
Search
Search
Sign In
Register
study help
business
intro stats
Stats Data And Models 4th Global Edition Richard D. De Veaux, Paul Velleman, David E. Bock - Solutions
Politics and sex One month before the election, a poll of 670 randomly selected voters showed 52% planning to vote for a certain candidate. A week later, it became known that he had had an extramarital affair, and a new poll showed only 49% of 1020 voters supporting him.Do these results indicate a
Birthweight The Journal of the American Medical Association reported a study examining the possible impact of air pollution caused by the 9/11 attack on New York’s World Trade Center on the weight of babies. Researchers found that 8% of 182 babies born to mothers who were exposed to heavy doses
Depression A study published in the Archives of General Psychiatry examined the impact of depression on a patient’s ability to survive cardiac disease.Researchers identified 450 people with cardiac disease, evaluated them for depression, and followed the group for 4 years. Of the 361 patients
Teen smoking A Vermont study published by the American Academy of Pediatrics examined parental influence on teenagers’ decisions to smoke. A group of students who had never smoked were questioned about their parents’ attitudes toward smoking. These students were questioned again two years later
Anorexia again In Exercise 34, you used a confidence interval to examine the effectiveness of Prozac in treating anorexia nervosa. Suppose that instead you had conducted a hypothesis test. (Answer these questions without actually doing the test.)a) What hypotheses would you test?b) State a
Another ear infection In Exercise 33, you used a confidence interval to examine the effectiveness of a vaccine against ear infections in babies. Suppose that instead you had conducted a hypothesis test. (Answer these questions without actually doing the test.)a) What hypotheses would you test?b)
Anorexia The Journal of the American Medical Association reported on an experiment intended to see if the drug Prozac® could be used as a treatment for the eating disorder anorexia nervosa. The subjects, women being treated for anorexia, were randomly divided into two groups. Of the 49 who
Ear infections A new vaccine was recently tested to see if it could prevent the painful and recurrent ear infections that many infants suffer from. The Lancet, a medical journal, reported a study in which babies about a year old were randomly divided into two groups. One group received
Race and smoking 2013 Data collected in 2013 by the Behavioral Risk Factor Surveillance System revealed that in the state of New Jersey, 14.7% of whites and 18.8% of blacks were cigarette smokers. Suppose these proportions were based on samples of 11,112 whites and 1916 blacks.a) Create a 90%
Prostate cancer There has been debate among doctors over whether surgery can prolong life among men suffering from prostate cancer, a type of cancer that typically develops and spreads very slowly. Recently, The New England Journal of Medicine published results of some Scandinavian research. Men
Carpal tunnel The painful wrist condition called carpal tunnel syndrome can be treated with surgery or less invasive wrist splints. Recently, Time magazine reported on a study of 176 patients. Among the half that had surgery, 80% showed improvement after three months, but only 48% of those who used
Pets Researchers at the National Cancer Institute released the results of a study that investigated the effect of weed-killing herbicides on house pets. They examined 827 dogs from homes where an herbicide was used on a regular basis, diagnosing malignant lymphoma in 473 of them. Of the 130 dogs
Graduation In October 2000, the U.S. Department of Commerce reported the results of a large-scale survey on high school graduation. Researchers contacted more than 25,000 Americans aged 24 years to see if they had finished high school; 84.9% of the 12,460 males and 88.1% of the 12,678 females
Arthritis The Centers for Disease Control and Prevention reported a survey of randomly selected Americans age 65 and older, which found that 410 of 1011 men and 550 of 1059 women suffered from some form of arthritis.a) Are the assumptions and conditions necessary for inference satisfied? Explain.b)
Buy it again? A consumer magazine plans to poll car owners to see if they are happy enough with their vehicles that they would purchase the same model again. They’ll randomly select 450 owners of American-made cars and 450 owners of Japanese models. Obviously, the actual opinions of the entire
Gender gap A presidential candidate fears he has a problem with women voters. His campaign staff plans to run a poll to assess the situation. They’ll randomly sample 350 men and 350 women, asking if they have a favorable impression of the candidate. Obviously, the staff can’t know this, but
Regulating access When a random sample of 935 parents were asked about rules in their homes, 77% said they had rules about the kinds of TV shows their children could watch. Among the 790 of those parents whose teenage children had Internet access, 85% had rules about the kinds of Internet sites
Revealing information Eight hundred eight-six randomly sampled teens were asked which of several personal items of information they thought it ok to share with someone they had just met. Forty-four percent said it was ok to share their e-mail addresses, but only 29%said they would give out their
Science news At the end of 2013, the Pew Project for Excellence in Journalism investigated where people are getting their news. In the study 22% of people 18–29 years old said they still read newspapers as one of their sources of news, while only 18% of people 30–49 said the same. What does it
Online social networking In September 2013, the Pew Internet and American Life Project surveyed American adults on their Facebook use. It found that 64% visited the site on a daily basis, up from 51% in 2010. What does it mean to say that the difference in proportions is“significant”?
Athletes, final inning Looking back at Exercise 12, instead of comparing the ages of players in Major League Baseball to players in the National Football League, what if they had compared the ages in Major League Baseball to a Little League composed of third graders? Would the pooled t-test be a
Cost of shopping, last look Looking back at Exercise 11, instead of comparing two very similar stores, suppose the researchers had compared purchases at two car dealerships:one that specializes in new Italian sports cars and another that carries used domestic vehicles. Would the pooled t-test be a
Athlete ages, one more time Repeat the test you did in Exercise 16, but assume that the variances of ages is the same in the two leagues. Did your conclusion change?Why do you think that is?
Cost of shopping, once more Repeat the test you did in Exercise 15, but assume that the variances of purchase amounts is the same at Target and Walmart. Did your conclusion change? Why do you think that is?
Athlete ages, three The researchers in Exercise 12 decide to test the hypothesis. The degrees of freedom formula gives 51.83 df. Test the null hypothesis at a = 0.05. Is the alternative one or two-sided?
Cost of shopping, three The researchers in Exercise 11 decide to test the hypothesis that the means are equal.The degrees of freedom formula gives 162.75 df. Test the null hypothesis at a = 0.05.
Athlete ages, again Using the summary statistics provided in Exercise 12, the sports reporter calculated the following 95% confidence interval for the mean difference between major league baseball players and professional football players. The 95% interval for mMLB - mNFL was ( -0.41, 3.09).
Cost of shopping, again Using the summary statistics provided in Exercise 11, researchers calculated a 95%confidence interval for the mean difference between Walmart and Target purchase amounts. The interval was ( - +14.15, - +1.85). Explain in context what this interval means.
Athlete ages A sports reporter suggests that professional baseball players must be, on average, older than professional football players, since football is a contact sport and players are more susceptible to concussions and serious injuries (www.sports.yahoo.com). One player was selected at random
Cost of shopping Do consumers spend more on a trip to Walmart or Target? Suppose researchers interested in this question collected a systematic sample from 85 Walmart customers and 80 Target customers by asking customers for their purchase amount as they left the stores. The data collected are
Non-profits, last one The researchers from Exercise 2 want to test if the proportions of satisfied employees are the same at for-profit companies as at not-for-profit companies.a) What is the difference in the proportions of the two types of companies?b) What is the pooled proportion of satisfied
Canada, la fin The researchers from Exercise 1 want to test if the proportions of foreign born are the same in the United States as in Canada.a) What is the difference in the proportions of foreign born residents from both countries?b) What is the pooled proportion of foreign born in both countries
Non-profits, again For the interval given in Exercise 6, explain what “95% confidence” means.
Canada, encore For the interval given in Exercise 5, explain what “95% confidence” means.
Non-profits, part 3 The researchers from Exercise 2 created a 95% two-proportion confidence interval for the difference in those who are “highly satisfied” when comparing people who work at non-profits to people who work at for-profit companies. Interpret the interval with a sentence in
Canada, trois The information in Exercise 1 was used to create a 95% two-proportion confidence interval for the difference between Canadians and Americans who were born in foreign countries. Interpret this interval with a sentence in context.95, confidence interval for pCanadians - pAmericans is
Non-profits, part 2 If the information in Exercise 2 is to be used to make inferences about all people who work at non-profits and for-profit companies, what conditions must be met before proceeding? List them and explain if they are met.
Canada, deux If the information in Exercise 1 is to be used to make inferences about the proportion all Canadians and all Americans born in other countries, what conditions must be met before proceeding? Are they met? Explain.
Non-profits Do people who work for non-profit organizations differ from those who work at for-profit companies when it comes to personal job satisfaction?Separate random samples were collected by a polling agency to investigate the difference. Data collected from 422 employees at non-profit
Canada Suppose an advocacy organization surveys 960 Canadians and 192 of them reported being born in another country (www.unitednorthamerica.org/simdiff.htm). Similarly, 170 out of 1250 Americans reported being foreign-born. Find the standard error of the difference in sample proportions.
Can you tell how much you are eating from how full you are? Or do you need visual cues? Researchers6 constructed a table with two ordinary 18 oz soup bowls and two identical-looking bowls that had been modified to slowly, imperceptibly, refill as they were emptied. They assigned experiment
Another concern of the study on teens’ online profiles was safety and privacy. In the random sample, girls were less likely than boys to say that they are easy to find online from their profiles. Only 19% (62 girls) of 325 teen girls with profiles say that they are easy to find, while 28% (75
A recent survey of 886 randomly selected teenagers (aged 12–17) found that more than half of them had online profiles.3 Some researchers and privacy advocates are concerned about the possible access to personal information about teens in public places on the Internet. There appear to be
Batteries We work for the “Watchdog for the Consumer”consumer advocacy group. We’ve been asked to look at a battery company that claims its batteries last an average of 100 hours under normal use. There have been several complaints that the batteries don’t last that long, so we decide to
And it means? Every statement about a confidence interval contains two parts—the level of confidence and the interval. Suppose that an insurance agent estimating the mean loss claimed by clients after home burglaries created the 95% confidence interval ($1644, $2391).a) What’s the margin of
Fritos® As a project for an Introductory Statistics course, students checked 6 bags of Fritos marked with a net weight of 35.4 grams. They carefully weighed the contents of each bag, recording the following weights(in grams): 35.5, 35.3, 35.1, 36.4, 35.4, 35.5. Is there evidence that the mean
Bread Clarksburg Bakery is trying to predict how many loaves to bake. In the past 100 days, the bakery has sold between 95 and 140 loaves per day. Here are a histogram and the summary statistics for the number of loaves sold for the past 100 days.a) Can you use these data to estimate the number of
Skin cancer In February 2012, MedPage Today reported that researchers used vemurafenib to treat metastatic melanoma (skin cancer). Out of 152 patients, 53% had a partial or complete response to vemurafenib.a) Write a 95% confidence interval for the proportion helped by the treatment, and interpret
Streams Researchers in the Adirondack Mountains collect data on a random sample of streams each year.One of the variables recorded is the substrate of the stream—the type of soil and rock over which they flow. The researchers found that 69 of the 172 sampled streams had a substrate of shale.
Occupy Wall Street In 2011, the Occupy Wall Street movement protested the concentration of wealth and power in the United States. A 2012 University of Delaware survey asked a random sample of 901 American adults whether they agreed or disagreed with the following statement:The Occupy Wall Street
Meals A college student is on a “meal program.” His budget allows him to spend an average of $10 per day for the semester. He keeps track of his daily food expenses for 2 weeks; the data are given in the table at the top of the following page. Is there strong evidence that he will overspend his
Petitions To get a voter initiative on a state ballot, petitions that contain at least 250,000 valid voter signatures must be filed with the Elections Commission. The board then has 60 days to certify the petitions. A group wanting to create a statewide system of universal health insurance has just
Speeding A newspaper report in August 2002 raised the issue of racial bias in the issuance of speeding tickets.The following facts were noted:■ Sixteen percent of drivers registered in New Jersey are black.■ Of the 324 speeding tickets issued in one month on a 65 mph section of the New Jersey
Women The U.S. Census Bureau reports that 26% of all U.S. businesses are owned by women. A Colorado consulting firm surveys a random sample of 410 businesses in the Denver area and finds that 115 of them have women owners. Should the firm conclude that its area is unusual? Test an appropriate
Dropouts One study comparing various treatments for the eating disorder anorexia nervosa initially enlisted 198 subjects, but found overall that 105 failed to complete their assigned treatment programs. Construct and interpret an appropriate confidence interval. Discuss any reservations you have
Name recognition, part II The advertising company described in Exercise 31 is thinking about signing a WNBA star to an endorsement deal. In its poll, 27% of the respondents could identify her.a) Fans who never took Statistics can’t understand why the company did not offer this WNBA player an
Name recognition An advertising agency won’t sign an athlete to do product endorsements unless it is sure the person is known to more than 25% of its target audience.The agency always conducts a poll of 500 people to investigate the athlete’s name recognition before offering a contract. Then it
Grade inflation In 1996, 20% of the students at a major university had an overall grade point average of 3.5 or higher (on a scale of 4.0). In 2012, a random sample of 1100 student records found that 25% had a GPA of 3.5 or higher. Is this evidence of grade inflation?
Approval 2008 Of all the post–World War II presidents, Richard Nixon had the highest disapproval rating near the end of his presidency. His disapproval rating peaked at 66% in July 1974, just before he resigned. This percentage has been considered by some pundits as a high water mark for
Power We are replicating an experiment. How will each of the following changes affect the power of our test?Indicate whether it will increase, decrease, or remain the same, assuming that all other aspects of the situation remain unchanged.a) We increase the number of subjects from 40 to 100.b) We
Fried PCs A computer company recently experienced a disastrous fire that ruined some of its inventory. Unfortunately, during the panic of the fire, some of the damaged computers were sent to another warehouse, where they were mixed with undamaged computers. The engineer responsible for quality
Safety Observers in Texas watched children at play in eight communities. Of the 814 children seen biking, roller skating, or skateboarding, only 14% wore a helmet.a) Create and interpret a 95% confidence interval.b) What concerns do you have about this study that might make your confidence interval
Errors An auto parts company advertises that its special oil additive will make the engine “run smoother, cleaner, longer, with fewer repairs.” An independent laboratory decides to test part of this claim. It arranges to use a taxicab company’s fleet of cars. The cars are randomly divided
Alcohol abuse Growing concern about binge drinking among college students has prompted one large state university to conduct a survey to assess the size of the problem on its campus. The university plans to randomly select students and ask how many have been drunk during the past week. If the
Teen smoking 2009 The Centers for Disease Control and Prevention say that about 19.5% of teenagers smoke tobacco (down from a high of 38% in 1997). A college has 522 students in its freshman class. Is it likely that more than 25% of them are smokers? Explain.
Church going In December 2011, Pew Research found that 921 American adults out of 2303 surveyed are active in a church, religious, or spiritual organization.a) Create a 95% confidence interval for the proportion of all American adults who are active in a church, religious, or spiritual
Cigarettes 2009 In 1999, the Centers for Disease Control and Prevention estimated that about 34.8% of high school students smoked cigarettes. They established a national health goal of reducing that figure to 16% by the year 2010. To that end, they would be on track if they achieved a reduction to
Language Neurological research has shown that in about 80% of people language abilities reside in the brain’s left side. Another 10% display right-brain language centers, and the remaining 10% have two-sided language control.(The latter two groups are mainly left-handers.)(Source: Science News,
Cheating A Rutgers University study found that many high school students cheat on tests. The researchers surveyed a random sample of 4500 high school students nationwide; 74% of them said they had cheated at least once.a) Create a 90% confidence interval for the level of cheating among high school
Largemouth bass Organizers of a fishing tournament believe that the lake holds a sizable population of largemouth bass. They assume that the weights of these fish have a model that is skewed to the right with a mean of 3.5 pounds and a standard deviation of 2.2 pounds.a) Explain why a skewed model
Teen deaths 2005 Traffic accidents are the leading cause of death among people aged 16 to 20. In May 2005, the National Highway Traffic Safety Administration reported that even though only 6.3% of licensed drivers are between 16 and 20 years old, they were involved in 12.6% of all fatal crashes.
Enough eggs? One of the important issues for poultry farmers is the production rate—the percentage of days on which a given hen actually lays an egg. Ideally, that would be 100% (an egg every day), but realistically, hens tend to lay eggs on about 3 of every 4 days. ISA Babcock wants to advertise
Polling disclaimer A newspaper article that reported the results of an election poll included the following explanation:The Associated Press poll on the 2012 presidential campaign is based on telephone interviews with 798 randomly selected registered voters from all states except Alaska and
Eggs The ISA Babcock Company supplies poultry farmers with hens, advertising that a mature B300 Layer produces eggs with a mean weight of 60.7 grams.Suppose that egg weights follow a Normal model with standard deviation 3.1 grams.a) What fraction of the eggs produced by these hens weigh more than
Archery A champion archer can generally hit the bull’s-eye 80% of the time. Suppose she shoots 200 arrows during competition. Let pn represent the percentage of bull’s-eyes she gets (the sample proportion).a) What are the mean and standard deviation of the sampling distribution model for pn?b)
Vitamin D 2012 In 2012, the American Journal of Clinical Nutrition reported that 31% of Australian adults over age 25 have a vitamin D deficiency. The data came from the AusDiab study of 11,218 Australians.a) Do these data meet the assumptions necessary for inference?What would you like to know
Bimodal We are sampling randomly from a distribution known to be bimodal.a) As our sample size increases, what’s the expected shape of the sample’s distribution?b) What’s the expected value of our sample’s mean?Does the size of the sample matter?c) How is the variability of sample means
Gay marriage In February 2014, Pew Research asked a random sample of 1821 U.S. adults, “Do you strongly favor, favor, oppose, or strongly oppose allowing gays and lesbians to marry legally?” (http://www.pewsocial
Net-Newsers In June 2008, the Pew Research Foundation sampled 3615 U.S. adults and asked about their choice of news sources. They identified 13% as“Net-Newsers” who regularly get their news from online sources rather than TV or newspapers.a) Pew reports a margin of error of ±2% for this
Dice When one die is rolled, the number of spots showing has a mean of 3.5 and a standard deviation of 1.7. Suppose you roll 10 dice. What’s the approximate probability that your total is between 30 and 40 (that is, the average for the 10 dice is between 3 and 4)? Specify the model you use and
Scrabble Using a computer to play many simulated games of Scrabble, researcher Charles Robinove found that the letter “A” occurred in 54% of the hands. This study had a margin of error of {10%. (Source: Chance, 15, no. 1[2002])a) Explain what the margin of error means in this context.b) Why
Babies The National Perinatal Statistics Unit of the Sydney Children’s Hospital reports that the mean birth weight of all babies born in birth centers in Australia in 2002 was 3564 grams—about 7.86 pounds. A Missouri hospital reports that the average weight of 112 babies born there last year
Leaky gas tanks Nationwide, it is estimated that 40%of service stations have gas tanks that leak to some extent. California is trying to lessen the prevalence of these leaks. We want to assess the effectiveness of their efforts by seeing if the percentage of service stations whose tanks leak has
Polling 2004 The 2004 U.S. presidential election was the last presidential election that had a significant third-party candidate. The official results showed that George W.Bush received 50.7% of the vote and John Kerry received 48.3%. Ralph Nader, running as a third-party candidate, picked up only
Hamsters How large are hamster litters? Among 47 golden hamster litters recorded, there were an average of 7.72 baby hamsters, with a standard deviation of 2.5 hamsters per litter.a) Create and interpret a 90% confidence interval.b) Would a 98% confidence interval have a larger or smaller margin of
Color-blind Medical literature says that about 8% of males are color-blind. A university’s introductory psychology course is taught in a large lecture hall. Among the students, there are 325 males. Each semester when the professor discusses visual perception, he shows the class a test for color
Crohn’s disease Omega-3 fatty acids have been tested as a means to prevent relapse of Crohn’s disease. Two large, randomized, placebo-controlled studies have shown no such benefit from omega-3 fatty acids. Suppose you are asked to design an experiment to further study this claim.Imagine that
Pottery An artist experimenting with clay to create pottery with a special texture has been experiencing difficulty with these special pieces. About 40% break in the kiln during firing. Hoping to solve this problem, she buys some more expensive clay from another supplier.She plans to make and fire
Hoops A basketball player with a poor foul-shot record practices intensively during the off-season. He tells the coach that he has raised his proficiency from 55% to 75%. Dubious, the coach asks him to take 10 shots, and is surprised when the player hits 9 out of 10. Did the player prove that he
Faulty or not? You are in charge of shipping computers to customers. You learn that a RAM chip was put into some of the machines. There’s a simple test you can perform, but it’s not perfect. All but 4% of the time, a good chip passes the test, but unfortunately, 35% of the bad chips pass the
Two coins In a drawer are two coins. They look the same, but one coin produces heads 84% of the time when spun while the other one produces heads only 28% of the time. You select one of the coins. You are allowed to spin it once and then must decide whether the coin is the 84%or the 28%-head coin.
Catheters, again The catheter company in Exercise 44 is reviewing its testing procedure.a) Suppose the significance level is changed to a = 0.01. Will the probability of a Type II error increase, decrease, or remain the same?b) What is meant by the power of the test the company conducts?c) Suppose
TV safety, revisited The manufacturer of the metal TV stands in Exercise 43 is thinking of revising its safety test.a) If the company’s lawyers are worried about being sued for selling an unsafe product, should they increase or decrease the value of a? Explain.b) In this context, what is meant by
Catheters During an angiogram, heart problems can be examined via a small tube (a catheter) threaded into the heart from a vein in the patient’s leg. It’s important that the company that manufactures the catheter maintain a diameter of 2.00 mm. (The standard deviation is quite small.) Each day,
TV safety The manufacturer of a metal stand for home TV sets must be sure that its product will not fail under the weight of the TV. Since some larger sets weigh nearly 300 pounds, the company’s safety inspectors have set a standard of ensuring that the stands can support an average of over 500
Testing the ads The company in Exercise 40 contacts 600 people selected at random, and only 133 remember the ad.a) Should the company renew the contract? Support your recommendation with an appropriate test.b) Explain what your P-value means in this context.
Software, part II 203 students signed up for the Stats course in Exercise 39. They used the software suggested by the salesman, and scored an average of 108 points on the final with a standard deviation of 8.7 points.a) Should the professor spend the money for this software?Support your
Ads A company is willing to renew its advertising contract with a local radio station only if the station can prove that more than 20% of the residents of the city have heard the ad and recognize the company’s product.The radio station conducts a random phone survey of 400 people.a) What are the
Software for learning A Statistics professor has observed that for several years students score an average of 105 points out of 150 on the semester exam. A salesman suggests that he try a statistics software package that gets students more involved with computers, predicting that it will increase
Stop signs Highway safety engineers test new road signs, hoping that increased reflectivity will make them more visible to drivers. Volunteers drive through a test course with several of the new- and old-style signs and rate which kind shows up the best.a) Is this a one-tailed or a two-tailed test?
Showing 2300 - 2400
of 5937
First
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Last
Step by Step Answers
Get 50% OFF
Claim Now
