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 5th Global Edition Richard De Veaux, Paul Velleman, David Bock - Solutions
Critical values For each of the following situations, find the critical value(s) for z or t.a) H0: p = 0.5 vs. HA: p • 0.5 at a = 0.05.b) H0: p = 0.4 vs. HA: p 7 0.4 at a = 0.05.c) H0: m = 10 vs. HA: m • 10 at a = 0.05; n = 36.d) H0: p = 0.5 vs. HA: p 7 0.5 at a = 0.01; n = 345.e) H0: m = 20
Alpha false and true Which of the following statements are true? If false, explain briefly.a) It is better to use an alpha level of 0.05 than an alpha level of 0.01.b) If we use an alpha level of 0.01, then a P-value of 0.001 is statistically significant.c) If we use an alpha level of 0.01, then we
Alpha true and false Which of the following statements are true? If false, explain briefly.a) Using an alpha level of 0.05, a P-value of 0.04 results in rejecting the null hypothesis.b) The alpha level depends on the sample size.c) With an alpha level of 0.01, a P-value of 0.10 results in rejecting
More P-values Which of the following are true? If false, explain briefly.a) A very low P-value provides evidence against the null hypothesis.b) A high P-value is strong evidence in favor of the null hypothesis.c) A P-value above 0.10 shows that the null hypothesis is true.d) If the null hypothesis
P-values Which of the following are true? If false, explain briefly.a) A very high P-value is strong evidence that the null hypothesis is false.b) A very low P-value proves that the null hypothesis is false.c) A high P-value shows that the null hypothesis is true.d) A P-value below 0.05 is always
False or true Which of the following are true? If false, explain briefly.a) If the null hypothesis is true, you’ll get a high P-value.b) If the null hypothesis is true, a P-value of 0.01 will occur about 1% of the time.c) A P-value of 0.90 means that the null hypothesis has a good chance of being
True or false Which of the following are true? If false, explain briefly.a) A P-value of 0.01 means that the null hypothesis is false.b) A P-value of 0.01 means that the null hypothesis has a 0.01 chance of being true.c) A P-value of 0.01 is evidence against the null hypothesis.d) A P-value of 0.01
Chips Ahoy! again As we learned in Chapter 17, Exercise 59, in 1998, as an advertising campaign, the Nabisco Company announced a “1000 Chips Challenge,” claiming that every 18-ounce bag of their Chips Ahoy! cookies contained at least 1000 chocolate chips. Dedicated statistics students at the
More ski wax From Chapter 17, Exercise 58, Bjork Larsen was trying to decide whether to use a new racing wax for crosscountry skis. He decided that the wax would be worth the price if he could average less than 55 seconds on a course he knew well, so he planned to study the wax by racing on the
More popcorn In Chapter 17, Exercise 57 we saw that Yvon Hopps ran an experiment to determine optimum power and time settings for microwave popcorn. His goal was to find a combination of power and time that would deliver high-quality popcorn with less than 10% of the kernels left unpopped, on
More Doritos We saw in Chapter 17, Exercise 56 that some students checked 6 bags of Doritos marked with a net weight of 28.3 grams. They carefully weighed the contents of each bag, recording the following weights (in grams): 29.2, 28.5, 28.7, 28.9, 29.1, 29.5.a) Do these data satisfy the
More Ruffles Recall from Chapter 17, Exercise 55 that students investigated the packaging of potato chips. They purchased 6 bags of Lay’s Ruffles marked with a net weight of 28.3 grams. They carefully weighed the contents of each bag, recording the following weights (in grams): 29.3, 28.2, 29.1,
AP Stats 2016 The College Board reported that 60.3% of all students who took the 2016 AP Statistics exam earned scores of 3 or higher. One teacher wondered if the performance of her school was better. She believed that year’s students to be typical of those who will take AP Stats at that school
John Wayne Like a lot of other Americans, John Wayne died of cancer. But is there more to this story? In 1955, Wayne was in Utah shooting the film The Conqueror. Across the state line, in Nevada, the United States military was testing atomic bombs.Radioactive fallout from those tests drifted across
TV ads A start-up company is about to market a new computer printer. It decides to gamble by running commercials during the Super Bowl. The company hopes that name recognition will be worth the high cost of the ads. The goal of the company is that over 40% of the public recognize its brand name and
Lost luggage An airline’s public relations department says that the airline rarely loses passengers’ luggage. It further claims that on those occasions when luggage is lost, 90% is recovered and delivered to its owner within 24 hours. A consumer group that surveyed a large number of air
Acid rain A study of the effects of acid rain on trees in a certain forest shows that 46 of 150 trees sampled exhibited some sort of damage from acid rain. This rate seemed to be higher than the 17% quoted in an ecosystem study report on the average proportion of damaged trees in the region. Does
Dropouts 2013 According to a report, the overall dropout average rate, which includes all students who do not complete upper secondary education, for a large country was around 15%. Subsequent studies show that the trend in the country is toward a decrease in the percentage of young people
Jury Census data for a certain county show that 19% of the adult residents are Hispanic. Suppose 72 people are called for jury duty and only 9 of them are Hispanic. Does this apparent underrepresentation of Hispanics call into question the fairness of the jury selection system? Explain.
Women executives A company is criticized because only 13 of 43 people in executive-level positions are women. The company explains that although this proportion is lower than it might wish, it’s not a surprising value given that only 40% of all its employees are women. What do you think? Test an
Seeds A garden center wants to store leftover packets of vegetable seeds for sale the following spring, but the center is concerned that the seeds may not germinate at the same rate a year later. The manager finds a packet of last year’s green bean seeds and plants them as a test. Although the
WebZine A magazine is considering the launch of an online edition. The magazine plans to go ahead only if it’s convinced that more than 25% of current readers would subscribe. The magazine contacted a Simple Random Sample of 500 current subscribers, and 137 of those surveyed expressed interest.
Football 2016 During the first 15 weeks of the 2016 season, the home team won 137 of the 238 regular-season National Football League games. Is this strong evidence of a home field advantage in professional football? Test an appropriate hypothesis and state your conclusion. Be sure the appropriate
Twins A national vital statistics report indicated that about 3%of all births produced twins. Is the rate of twin births the same among very young mothers? Data from a large city hospital found that only 7 sets of twins were born to 469 teenage girls.Test an appropriate hypothesis and state your
Scratch and dent An appliance manufacturer stockpiles washers and dryers in a large warehouse for shipment to retail stores.Sometimes in handling them the appliances get damaged. Even though the damage may be minor, the company must sell those machines at drastically reduced prices. The company
Pollution A company with a fleet of 150 cars found that the emissions systems of 7 out of the 22 they tested failed to meet pollution control guidelines. Is this strong evidence that more than 20% of the fleet might be out of compliance? Test an appropriate hypothesis and state your conclusion. Be
Take the offer II We saw in Chapter 16, Exercise 36 that Top One tested the effectiveness of a double-miles campaign by recently sending out offers to a random sample of 100,000 cardholders. Of those, 2468 registered for the promotion. Even though this is nearly a 2.5% rate, a staff member suspects
Contributions, please II We learned in Chapter 16, Exercise 35 that the Care Association for the Blind recently sent letters to a random sample of 50,000 potential donors and received 2380 donations. They’ve had a contribution rate of 5.5% in past campaigns, but a staff member worries that the
Educated mothers According to a Ministry of Education report for a large region, 42% of students reported that their mothers had graduated from college. In a survey conducted in a given year, responses from 7500 students in the region found that this figure had grown to 43%. Is this evidence of an
Absentees A certain Ministry of Education report states that 35% of students in a large region had not been absent from school even once during the previous month. In a survey conducted in a given year, responses from 7500 students in the region showed that this figure had increased to 36.1%.
Candy Someone hands you a box of a dozen chocolate-covered candies, telling you that half are vanilla creams and the other half peanut butter. You pick candies at random and discover the first three you eat are all vanilla.a) If there really were 6 vanilla and 6 peanut butter candies in the box,
He cheats? A friend of yours claims that when he tosses a coin he can control the outcome. You are skeptical and want him to prove it. He tosses the coin, and you call heads; it’s tails.You try again and lose again.a) Do two losses in a row convince you that he really can control the toss?
Cars A survey investigating whether the proportion of today’s high school seniors who own their own cars is higher than it was a decade ago finds a P-value of 0.017. Is it reasonable to conclude that more high schoolers have cars? Explain.
Relief A company’s old antacid formula provided relief for 70% of the people who used it. The company tests a new formula to see if it is better and gets a P-value of 0.27. Is it reasonable to conclude that the new formula and the old one are equally effective? Explain.
We don’t believe that claim, and roll the die 200 times to test an appropriate hypothesis. Our P-value turns out to be 0.03. Which conclusion is appropriate? Explain.a) There’s a 3% chance that the die is fair.b) There’s a 97% chance that the die is fair.c) There’s a 3% chance that a loaded
Dice The seller of a loaded die claims that it will favor the outcome
Negatives After the political ad campaign described in Exercise 15, parta, pollsters check the governor’s negatives.They test the hypothesis that the ads produced no change against the alternative that the negatives are now below 30% and find a P-value of 0.22. Which conclusion is appropriate?
More hypotheses Write the null and alternative hypotheses you would use to test each situation.a) In the 1950s, only about 40% of high school graduates went on to college. Has the percentage changed?b) Twenty percent of cars of a certain model have needed costly transmission work after being driven
Hypotheses Write the null and alternative hypotheses you would use to test each of the following situations:a) A governor is concerned about his “negatives”—the percentage of state residents who express disapproval of his job performance.His political committee pays for a series of TV ads,
Expensive medicine Developing a new drug can be an expensive process, resulting in high costs to patients. A pharmaceutical company has developed a new drug to reduce cholesterol, and it will conduct a clinical trial to compare the effectiveness to the most widely used current treatment. The
Bad medicine Occasionally, a report comes out that a drug that cures some disease turns out to have a nasty side effect. For example, some antidepressant drugs may cause suicidal thoughts in younger patients. A researcher wants to study such a drug and look for evidence of a side effect.a) If the
Golf balls The United States Golf Association (USGA) sets performance standards for golf balls. For example, the initial velocity of the ball may not exceed 250 feet per second when measured by an apparatus approved by the USGA. Suppose a manufacturer introduces a new kind of ball and provides a
Pizza A researcher tests whether the mean cholesterol level among those who eat frozen pizza exceeds the value considered to indicate a health risk. She gets a P-value of 0.07. Explain in this context what the “7%” represents.
Marriage In 1970, a European study indicated that the age at which women first married in Europe had a mean of 22.7 years.It is widely suspected that young people today are waiting longer to get married. We want to find out if the mean age of first marriage has increased since
GRE performance again Instead of advertising the percentage of customers who improve by at least 10 points, a manager suggests testing whether the mean score improves at all. For each customer they record the difference in score before and after taking the course (After - Before).a) State the null
Seasonal rentals According to a recent study conducted by the Paris city hall, 7% of apartments in the first four districts are rented on a seasonal basis. The mayor of the 10th district wonders if the rate in the district is different from this. He randomly selects 800 apartments in his district
Brexit According to the EU Referendum results in 2016, 51.9% of the United Kingdom has voted to leave the European Union. Before the official results were disclosed, the Wealden District Council had predicted that they will have a higher proportion of people in favor of leaving the United Kingdom.
GRE performance A test preparation company claims that more than 50% of the students who take their GRE prep course improve their scores by at least 10 points.a) Is the alternative to the null hypothesis more naturally one-sided or two-sided? Explain.b) A test run with randomly selected
Better than aspirin again? Referring to the study of Exercise 1:a) Is the alternative to the null hypothesis more naturally one-sided or two-sided? Explain.b) The P-value from a clinical trial testing the hypothesis is 0.0031. What do you conclude?c) What would you have concluded if the P-value had
Hypotheses and parameters As in Exercise 3, for each of the following situations, define the parameter and write the null and alternative hypotheses in terms of parameter values.a) Seat-belt compliance among university students in Kuala Lumpur was 40% in 1993. The city wants to know if it has
Parameters and hypotheses For each of the following situations, define the parameter (proportion, probability, or mean), and write the null and alternative hypotheses in terms of parameter values.Example: We want to know if the proportion of “up days” in the stock market is 50%. Answer: Let p =
Psychic Your friend claims to be psychic. You are skeptical.To test this, you take a deck of 52 playing cards and have your friend try to identify the color of the card (black or red), without looking, of course! State the null hypothesis for your experiment.
Better than aspirin? A very large study showed that aspirin reduced the rate of first heart attacks by 42%. A pharmaceutical company thinks they have a drug that will be more effective than aspirin and plans to do a randomized clinical trial to test the new drug. What is the null hypothesis the
Teachers Software analysis of the salaries of a random sample of 300 London teachers produced the confidence interval shown below. Which conclusion is correct? What’s wrong with the others?t-Interval for m:with 95% Confidence 44489 6 m(TchPay) 6 48244a) If we took many random samples of 300
Cattle Livestock are given a special feed supplement to see if it will promote weight gain. Researchers report that the 77 cows studied gained an average of 56 pounds, and that a 95% confidence interval for the mean weight gain this supplement produces has a margin of error of {11 pounds. Some
Salaries A survey finds that a 99% confidence interval for the mean salary of a police patrol officer in Paris, France, in 2018 is €33,876 and €58,073. A student is surprised that such few police officers make more than $57,000. Explain what is wrong with the student’s interpretation.
Home sales revisited For the confidence interval you found in Exercise 11, interpret this interval and explain what 95% confidence means in this context.
Home sales again In the previous exercise, you found a 95%confidence interval to estimate the average loss in home value.a) Suppose the standard deviation of the losses had been $3000 instead of $1500. What would the larger standard deviation do to the width of the confidence interval (assuming the
Home sales The housing market recovered slowly from the economic crisis of 2008. Recently, in one large community, realtors randomly sampled 36 bids from potential buyers to estimate the average loss in home value. The sample showed the average loss from the peak in 2008 was $9560 with a standard
t-models, part IV Describe how the critical value of t for a 95% confidence interval changes as the number of degrees of freedom increases.
t-models, part III Describe how the shape, center, and spread of t-models change as the number of degrees of freedom increases.
t-models, part II Using the t-tables, software, or a calculator, estimatea) the critical value of t for a 95% confidence interval with dƒ = 7.b) the critical value of t for a 99% confidence interval with dƒ = 102.
t-models, part I Using the t-tables, software, or a calculator, estimatea) the critical value of t for a 98% confidence interval with dƒ = 13.b) the critical value of t for a 90% confidence interval with dƒ = 95.
More groceries Suppose the store in Exercise 4 had 300 customers this Sunday.a) Estimate the probability that the store’s revenues were at least $9,000.b) If, on a typical Sunday, the store serves 300 customers, how much does the store take in on the “best” 10% of such days?
More tips The waiter in Exercise 3 usually waits on about 50 parties over a weekend of work.a) Estimate the probability that he will earn at least $550 in tips.b) How much does he earn on the “worst” 10% of such weekends?
Groceries A grocery store’s receipts show that Sunday customer purchases have a skewed distribution with a mean of$28 and a standard deviation of $20.a) Explain why you cannot determine the probability that the next Sunday customer will spend at least $34.b) Can you estimate the probability that
Tips A waiter believes the distribution of his tips has a model that is slightly skewed to the right, with a mean of $8.50 and a standard deviation of $4.30.a) Explain why you cannot determine the probability that a given party will tip him at least $18 using the Normal model.b) Can you estimate
LSAT The LSAT (a test taken for law school admission) has a mean score of 151 with a standard deviation of 9 and a unimodal, symmetric distribution of scores. A test preparation organization teaches small classes of 9 students at a time.A larger organization teaches classes of 25 students at a
Salmon A specialty food company sells whole King Salmon to various customers. The mean weight of these salmon is 35 pounds with a standard deviation of 2 pounds. The company ships them to restaurants in boxes of 4 salmon, to grocery stores in cartons of 16 salmon, and to discount outlet stores in
Amendment A TV news reporter says that a proposed constitutional amendment is likely to win approval in the upcoming election because a poll of 1505 likely voters indicated that 52%would vote in favor. The reporter goes on to say that the margin of error for this poll was 3%.a) Explain why the poll
Approval rating A newspaper reports that the governor’s approval rating stands at 65%. The article adds that the poll is based on a random sample of 972 adults and has a margin of error of 2.5%.What level of confidence did the pollsters use?
Back to campus II Suppose ACT, Inc. wants to update their information from Exercise 46 on the percentage of freshmen that return for a second year of college.a) They want to cut the stated margin of error in half. How many college freshmen must be surveyed?b) Do you have any concerns about this
Deer ticks Wildlife biologists inspect 153 deer taken by hunters and find 32 of them carrying ticks that test positive for Lyme disease.a) Create a 90% confidence interval for the percentage of deer that may carry such ticks.b) If the scientists want to cut the margin of error in half, how many
Back to campus ACT, Inc. reported that 74% of 1644 randomly selected college freshmen returned to college the next year. The study was stratified by type of college—public or private. The retention rates were 71.9% among 505 students enrolled in public colleges and 74.9% among 1139 students
Privacy or security? In January 2014 AP-GfK polled 1060 U.S. adults to find if people were more concerned with privacy or security. Privacy concerns outweighed concerns about being safe from terrorists for 646 out of the 1060 polled. Of the 1060 adults, about 180 are 65 and older and their concerns
Private tuition A 2018 Sutton Trust survey found that 27% of young people in England and Wales attended private tuition.This poll was based on a random sample of 2381 young people aged between 11 and 16.(Source: https://www.suttontrust.com/newsarchive/27-ofpupils-pay-to-have-private-tuition/)a)
Rickets Vitamin D, whether ingested as a dietary supplement or produced naturally when sunlight falls on the skin, is essential for strong, healthy bones. The bone disease rickets was largely eliminated in England during the 1950s, but now there is concern that a generation of children more likely
Gambling A city ballot includes a local initiative that would legalize gambling. The issue is hotly contested, and two groups decide to conduct polls to predict the outcome. The local newspaper finds that 53% of 1200 randomly selected voters plan to vote “yes,” while a college statistics class
Death penalty, again In the survey on the death penalty you read about in the Step-by-Step Example, the Gallup Poll actually split the sample at random, asking 510 respondents the question quoted earlier, “Generally speaking, do you believe the death penalty is applied fairly or unfairly in this
Local news The mayor of a small city has suggested that the state locate a new prison there, arguing that the construction project and resulting jobs will be good for the local economy.A total of 183 residents show up for a public hearing on the proposal, and a show of hands finds only 31 in favor
Safe food Some food retailers propose subjecting food to a low level of radiation in order to improve safety, but the sale of such “irradiated” food is opposed by many people. Suppose a grocer wants to find out what his customers think. He has cashiers distribute surveys at checkout and ask
Junk mail Direct mail advertisers send solicitations (a.k.a.“junk mail”) to thousands of potential customers in the hope that some will buy the company’s product. The acceptance rate is usually quite low. Suppose a company wants to test the response to a new flyer, and sends it to 1000 people
Teenage drivers An insurance company checks police records on 582 accidents selected at random and notes that teenagers were at the wheel in 91 of them.a) Create a 95% confidence interval for the percentage of all auto accidents that involve teenage drivers.b) Explain what your interval means.c)
Take the offer Top One, a major credit card company, is planning a new offer for their current cardholders. The offer will give double airline miles on purchases for the next 6 months if the cardholder goes online and registers for the offer.To test the effectiveness of the campaign, Top One
Contributions, please The Care Association for the Blind is a philanthropic organization that relies on contributions. They send free mailing labels and greeting cards to potential donors on their list and ask for a voluntary contribution. To test a new campaign, they recently sent letters to a
Still living online The Digital Clarity poll described in Exercise 5 found that 16% of a sample of 1300 UK young adults (ages 18–25) go online several times a day. (Treat this as a Simple Random Sample.)a) Find the margin of error for this poll if we want 95%confidence in our estimate of the
Baseball fans In a poll taken in December 2012, Gallup asked 1006 national adults whether they were baseball fans; 48% said they were. Almost five years earlier, in February 2008, only 35% of a similar-size sample had reported being baseball fans.a) Find the margin of error for the 2012 poll if we
Mislabeled fish, second course A study similar to the one described in Exercise 31 found that 12 of 30 “red snapper”packages tested were a different kind of fish.a) Are the conditions for creating a confidence interval satisfied? Explain.b) Construct a 95% confidence interval.c) Explain what
Mislabeled fish In 2010, biologists from University College Dublin (https://www.ucd.ie/news/2010/04APR10/230410_cod.html) analyzed 156 samples of fish sold as “cod” or “haddock” in Ireland using DNA barcoding to genetically identify the species of the fish. Laboratory results indicated that
Parole A study of 902 decisions (to grant parole or not) made by the Nebraska Board of Parole produced the following computer output. Assuming these cases are representative of all cases that may come before the Board, what can you conclude?z-Interval for proportion With 95.00% confidence,
Cars What fraction of cars made in Japan? The computer output below summarizes the results of a random sample of 50 autos. Explain carefully what it tells you.z-Interval for proportion With 90.00% confidence, 0.29938661 6 P(japan) 6 0.46984416
Confidence intervals, again Several factors are involved in the creation of a confidence interval. Among them are the sample size, the level of confidence, and the margin of error. Which statements are true?a) For a given sample size, reducing the margin of error will mean lower confidence.b) For a
Confidence intervals Several factors are involved in the creation of a confidence interval. Among them are the sample size, the level of confidence, and the margin of error. Which statements are true?a) For a given sample size, higher confidence means a smaller margin of error.b) For a specified
More conclusions In January 2002, two students made worldwide headlines by spinning a Belgian euro 250 times and getting 140 heads—that’s 56%. That makes the 90% confidence interval(51%, 61%). What does this mean? Are these conclusions correct?Explain.a) Between 51% and 61% of all euros are
Conclusions A catalog sales company promises to deliver orders placed on the Internet within 3 days. Follow-up calls to a few randomly selected customers show that a 95% confidence interval for the proportion of all orders that arrive on time is 88% { 6%. What does this mean? Are these conclusions
More conditions Consider each situation described. Identify the population and the sample, explain what p and pn represent, and tell whether the methods of this chapter can be used to create a confidence interval.a) A consumer group hoping to assess customer experiences with auto dealers surveys
Conditions For each situation described below, identify the population and the sample, explain what p and pn represent, and tell whether the methods of this chapter can be used to create a confidence interval.a) Police set up an auto checkpoint at which drivers are stopped and their cars inspected
Another margin of error A medical researcher estimates the percentage of children exposed to lead-based paint, adding that he believes his estimate has a margin of error of about 4%.Explain what the margin of error means.
Margin of error A TV newscaster reports the results of a poll of voters and then says, “The margin of error is plus or minus 3%.” Explain carefully what that means.
Hiring In preparing a report on the economy, we need to estimate the percentage of businesses that plan to hire additional employees in the next 60 days.a) How many randomly selected employers must we contact in order to create an estimate in which we are 98% confident with a margin of error of
Showing 1100 - 1200
of 5937
First
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
Last
Step by Step Answers
Get 50% OFF
Claim Now
