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engineering
introduction to matlab
Stats Data And Models 5th Edition Richard D De Veaux, Paul F Velleman, David E Bock - Solutions
Satisfied respondents The company’s annual report states, “Our survey shows that 87.34% of our employees are ‘very happy’ working here.” Comment on that claim. Use appropriate statistics terminology.
Another fish story In recent years, beaches around the world have seen fish washing up on shore in large numbers. One group of scientists thought that leakage from the damaged Fukushima nuclear power plant in Japan might be a cause. They propose to measure the mean amount of radiation in a sample
The journal Circulation reported that among 1900 people who had heart attacks, those who drank an average of 19 cups of tea a week were 44% more likely than nondrinkers to survive at least 3 years after the attack.
Widely used antidepressants may reduce ominous brain plaques associated with Alzheimer’s disease. In the study, mice genetically engineered to have large amounts of brain plaque were given a class of antidepressants that boost serotonin in the brain. After a single dose, the plaque levels
An orange-juice processing plant will accept a shipment of fruit only after several hundred oranges selected from various locations within the truck are carefully inspected. If too many show signs of unsuitability for juice (bruised, rotten, unripe, etc.), the whole truckload is rejected.
Older Americans with a college education are significantly more likely to be emotionally well-off than are people in this age group with less education. Among those aged 65 and older, 35% scored 90 or above on the Emotional Health Index, but for those with a college degree, the percentage rose to
Cell phone risks Researchers at the Washington University School of Medicine randomly placed 480 rats into one of three chambers containing radio antennas. One group was exposed to digital cell phone radio waves, the second to analog cell phone waves, and the third group to no radio waves. Two
Tips In restaurants, servers rely on tips as a major source of income. Does serving candy after the meal produce larger tips? To find out, two waiters determined randomly whether or not to give candy to 92 dining parties. They recorded the sizes of the tips and reported that guests getting candy
Tips, take 2 In another experiment to see if getting candy after a meal would induce customers to leave a bigger tip, a waitress randomly decided what to do with 80 dining parties. Some parties received no candy, some just one piece, and some two pieces. Others initially got just one piece of
Timing In August 2011, a Sodahead.com voluntary response poll asked site visitors, “Obama is on Vacation Again: Does He Have the Worst Timing Ever?” 56% of the 629 votes were for “Yes.” During the week of the poll, a 5.8 earthquake struck near Washington, D.C., and Hurricane Irene made its
Laundry An experiment to test a new laundry detergent, SparkleKleen, is being conducted by a consumer advocate group. They would like to compare its performance with that of a laboratory standard detergent they have used in previous experiments. They can stain 16 swatches of cloth with 2 tsp of a
How long is 30 seconds? Sofie, Ryan, and Alessandra wanted to design an experiment to find out how distraction affects our ability to judge time. The experiment consisted of starting a clock (out of view of the subject) and then asking the subject to tell them when they thought 30 seconds had
Cookies Mary Beth, Nigel, and Molly want to design an experiment to find the recipe for the best chocolate chip cookies. They will try to keep the size of the cookies the same, but use cooking times of 10 and 15 minutes. They will use three different temperatures: 325° F, 375° F and 425° F and
Smoking and Alzheimer’s Medical studies indicate that smokers are less likely to develop Alzheimer’s disease than people who never smoked.1. Does this prove that smoking may offer some protection against Alzheimer’s? Explain.2. Offer an alternative explanation for this association.3. How
Antacids A researcher wants to compare the performance of three types of antacid in volunteers suffering from acid reflux disease. Because men and women may react differently to this medication, the subjects are split into two groups, by sex. Subjects in each group are randomly assigned to take one
Sex and violence Does the content of a television program affect viewers’ memory of the products advertised in commercials? Design an experiment to compare the ability of viewers to recall brand names of items featured in commercials during programs with violent content, sexual content, or
Pubs In England, a Leeds University researcher said that the local watering hole’s welcoming atmosphere helps men get rid of the stresses of modern life and is vital for their psychological well-being. Author of the report, Dr. Colin Gill, said rather than complain, women should encourage men to
Toasters again In a batch of 10,000 toasters, what are the chances that fewer than 450 need to be returned?
Sell! A car dealership sells an average of 5 cars in a day. Using the Poisson model, what is the probability that the dealer sells 3 cars tomorrow?
Passing on A large hospital has an average of 7 fatalities in a week. Using the Poisson model, what is the probability that this week it has 10 fatalities?
Child’s play In a board game you determine the number of spaces you may move by spinning a spinner and rolling a die. The spinner has three regions: Half of the spinner is marked “5,” and the other half is equally divided between “10” and “20.” The six faces of the die show 0, 0, 1,
Customer center operator Raaj works at the customer service call center of a major credit card bank. Cardholders call for a variety of reasons, but regardless of their reason for calling, if they hold a platinum card, Raaj is instructed to offer them a double-miles promotion. About 10% of all
Cold calls Justine works for an organization committed to raising money for Alzheimer’s research. From past experience, the organization knows that about 20% of all potential donors will agree to give something if contacted by phone. They also know that of all people donating, about 5% will give
Merger Explain why the facts you know about variances of independent random variables might encourage two small insurance companies to merge.
Color blindness About 8% of males are color-blind. A researcher needs some color-blind subjects for an experiment and begins checking potential subjects.1. On average, how many men should the researcher expect to check to find one who is color-blind?2. What’s the probability that she won’t find
Coins and intuition If you flip a fair coin 100 times,1. Intuitively, how many heads do you expect?2. Use the formula for expected value to verify your intuition.
Travel to Kyrgyzstan Your pocket copy of Kyrgyzstan on 4237±360 Som a Day claims that you can expect to spend about 4237 som each day with a standard deviation of 360 som. How well can you estimate your expenses for the trip?1. Your budget allows you to spend 90,000 som. To the nearest day, how
Picking melons Two stores sell watermelons. At the first store the melons weigh an average of 22 pounds, with a standard deviation of 2.5 pounds. At the second store the melons are smaller, with a mean of 18 pounds and a standard deviation of 2 pounds. You select a melon at random at each store.1.
Home, sweet home According to the 2000 Census, 66% of U.S. households own the home they live in. A mayoral candidate conducts a survey of 820 randomly selected homes in your city and finds only 523 owned by the current residents. The candidate then attacks the incumbent mayor, saying that there is
Jerseys A Statistics professor comes home to find that all four of his children got white team shirts from soccer camp this year. He concludes that this year, unlike other years, the camp must not be using a variety of colors. But then he finds out that in each child’s age group there are 4
Technology on campus Every 5 years the Conference Board of the Mathematical Sciences surveys college math departments. In 2000 the board reported that 51% of all undergraduates taking Calculus I were in classes that used graphing calculators and 31% were in classes that used computer assignments.
Dogs A census by the county dog control officer found that 18% of homes kept one dog as a pet, 4% had two dogs, and 1% had three or more. If a salesman visits two homes selected at random, what’s the probability he encounters1. No dogs?2. Some dogs?3. Dogs in each home?4. More than one dog in
Frogs A wildlife biologist examines frogs for a genetic trait he suspects may be linked to sensitivity to industrial toxins in the environment. Previous research had established that this trait is usually found in 1 of every 8 frogs. He collects and examines a dozen frogs. If the frequency of the
Coins A coin is to be tossed 36 times.1. What are the mean and standard deviation of the number of heads?2. Suppose the resulting number of heads is unusual, two standard deviations above the mean. How many “extra” heads were observed?3. If the coin were tossed 100 times, would you still
Apples An orchard owner knows that he’ll have to use about 6% of the apples he harvests for cider because they will have bruises or blemishes. He expects a tree to produce about 300 apples.1. Describe an appropriate model for the number of cider apples that may come from that tree. Justify your
The Drake equation In 1961 astronomer Frank Drake developed an equation to try to estimate the number of extraterrestrial civilizations in our galaxy that might be able to communicate with us via radio transmissions. Now largely accepted by the scientific community, the Drake equation has helped
Recalls In a car rental company’s fleet, 70% of the cars are American brands, 20% are Japanese, and the rest are German. The company notes that manufacturers’ recalls seem to affect 2% of the American cars, but only 1% of the others.1. What’s the probability that a randomly chosen car is
Pregnant? Suppose that 70% of the women who suspect they may be pregnant and purchase an in-home pregnancy test are actually pregnant. Further suppose that the test is 98% accurate. What’s the probability that a woman whose test indicates that she is pregnant actually is?
Door prize You are among 100 people attending a charity fundraiser at which a large-screen TV will be given away as a door prize. To determine who wins, 99 white balls and 1 red ball have been placed in a box and thoroughly mixed. The guests will line up and, one at a time, pick a ball from the
Annoying phone calls A newly hired telemarketer is told he will probably make a sale on about 12% of his phone calls. The first week he called 200 people, but only made 10 sales. Should he suspect he was misled about the true success rate? Explain.
ESP Scientists wish to test the mind-reading ability of a person who claims to have ESP. They use five cards with different and distinctive symbols (square, circle, triangle, line, squiggle). Someone picks a card at random and thinks about the symbol. The “mind reader” must correctly identify
TB Worldwide, tuberculosis is the number-one cause of death from an infectious disease. But the majority of cases are in developing countries. In the U.S., the probability of contracting TB is small, with p about 0.0005 for a new case in a given year. In a town of 8000 people:1. What’s the
True–false A true–false test consists of 50 questions. How many does a student have to get right to convince you that he is not merely guessing? Explain.
Living online Pew Research, in 2015, polled a random sample of 1060 U.S. teens (ages 13–17) about Internet use. 56% of those teens reported going online several times a day—a fact of great interest to advertisers.1. Explain the meaning of p^=0.56 in the context of this situation.2. Calculate
Hot hand A basketball player who ordinarily makes about 55% of his free throw shots has made 4 in a row. Is this evidence that he has a “hot hand” tonight? That is, is this streak so unusual that it means the probability he makes a shot must have changed? Explain.
Spanking In a 2015 Pew Research study on trends in marriage and family (www.pewsocialtrends.org/2015/12/17/1-the-american-family-today/), 53% of randomly selected parents said that they never spank their children. The 95% confidence interval is from 50.6% to 55.4% (n=1807).1. Interpret the interval
Wrong direction An Ipsos/Reuters poll of 2214 U.S. adults voters in April and May 2017 asked a standard polling question of whether the United States was headed in the “Right Direction” or was on the “Wrong Track.” 54% said that things are on the wrong track vs. 33% who said “right
Salaries A survey finds that a 95% confidence interval for the mean salary of a police patrol officer in Fresno, California, in 2016 is $52,516 to $53,509. A student is surprised that so few police officers make more than $53,500. Explain what is wrong with the student’s interpretation.
Bird counts A biology class conducts a bird count every week during the semester. Using the number of species counted each week, a student finds the following confidence interval for the mean number of species counted:Knowing that species have to be whole numbers, the student reports that 95% of
Dice The seller of a loaded die claims that it will favor the outcome 6. 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
Cholesterol According to the National Institutes of Health (NIH) adults should have a total cholesterol level of below 240 mg/dL. The dataset Framingham contains the total cholesterol levels of 1406 participants in the Framingham Heart Study.a. Find the mean total cholesterol of these
Blood Only 4% of people have Type AB blood.1. On average, how many donors must be checked to find someone with Type AB blood?2. What’s the probability that there is a Type AB donor among the first 5 people checked?3. What’s the probability that the first Type AB donor will be found among the
Movies 06-15 How have movies changed during the decade from 2006 to 2015? Here is a contingency table showing the proportion of movies with each of the MPAA categories in each year:1. Are these column percents or row percents? How can you tell?2. Does it look like things have changed much between
Job hunting A June 2011 Gallup Poll asked Americans, “Thinking about the job situation in America today, would you say that it is now a good time or a bad time to find a quality job?” The choices were “Good time” or “Bad time.” What kind of variable is the response?
Togetherness Are good grades in high school associated with family togetherness? A random sample of 142 high school students was asked how many meals per week their families ate together. Their responses produced a mean of 3.78 meals per week, with a standard deviation of 2.2. Researchers then
Indicators For each of these potential predictor variables, say whether they should be represented in a regression model by indicator variables. If so, then suggest what specific indicators should be used (that is, what values they would have).1. In a regression to predict income, the sex of
Parking lots Sensors in parking lots are able to detect and communicate when spaces are filled in a large covered parking garage next to an urban shopping mall. How might the owners of the parking garage use this information both to attract customers and to help the store owners in the mall make
Satellites and global climate change Satellites send back nearly continuous data on the earth’s land masses, oceans, and atmosphere from space. How might researchers use this information in both the short and long terms to help study changes in the earth’s climate?
Nobel laureates The website www.nobelprize.org allows you to look up all the Nobel prizes awarded in any year. The data are not listed in a table. Rather you drag a slider to the year and see a list of the awardees for that year. Describe the Who in this scenario.
Facebook. Facebook uploads more than 350 million photos every day onto its servers. For this collection, describe the Who and the What.
Voters A February 2010 Gallup Poll question asked, “In politics, as of today, do you consider yourself a Republican, a Democrat, or an Independent?” The possible responses were “Democrat,” “Republican,” “Independent,” “Other,” and “No Response.” What kind of variable is the
Medicine A pharmaceutical company conducts an experiment in which a subject takes 100 mg of a substance orally. The researchers measure how many minutes it takes for half of the substance to exit the bloodstream. What kind of variable is the company studying?
Voting and elections Pollsters are interested in predicting the outcome of elections. Give an example of how they might model whether someone is likely to vote.
Weather Meteorologists utilize sophisticated models to predict the weather up to ten days in advance. Give an example of how they might assess their models.
The news Find a newspaper or magazine article in which some data are reported. For the data discussed in the article, identify as many of the W’s as you can. Include a copy of the article with your report.
Gaydar A study conducted by a team of American and Canadian researchers found that during ovulation, a woman can tell whether a man is gay or straight by looking at his face. To explore the subject, the authors conducted three investigations, the first of which involved 40 undergraduate women who
Hula-hoops The hula-hoop, a popular children’s toy in the 1950s, has gained popularity as an exercise in recent years. But does it work? To answer this question, the American Council on Exercise conducted a study to evaluate the cardio and calorie-burning benefits of “hooping.” Researchers
Kentucky Derby 2018 on the computer Load the Kentucky Derby 2018 data into your preferred statistics package and answer the following questions;1. What was the name of the winning horse in 1880?2. When did the length of the race change?3. What was the winning time in 1974?4. Only one horse has run
Indy 500 2018 on the computer Load the Indy 500 2018 data into your preferred statistics package and answer the following questions:a. What was the average speed of the winner in 1920?b. How many times did Bill Vukovich win the race in the 1950s?c. How many races took place during the 1940s?
Graphs in the news Find a bar chart of categorical data from a newspaper, a magazine, or the Internet.1. Is the graph clearly labeled?2. Does it violate the area principle?3. Does the accompanying article tell the W’s of the variable?4. Do you think the article correctly interprets the data?
Graphs in the news II Find a pie chart of categorical data from a newspaper, a magazine, or the Internet.1. Is the graph clearly labeled?2. Does it violate the area principle?3. Does the accompanying article tell the W’s of the variable?4. Do you think the article correctly interprets the data?
Tables in the news Find a frequency table of categorical data from a newspaper, a magazine, or the Internet.1. Is it clearly labeled?2. Does it display percentages or counts?3. Does the accompanying article tell the W’s of the variable?4. Do you think the article correctly interprets the data?
Tables in the news II Find a table of categorical data from a newspaper, a magazine, or the Internet.1. Is it clearly labeled?2. Does it display percentages or counts?3. Does the accompanying article tell the W’s of the variables?4. Do you think the article correctly interprets the data?
Not a histogram Find a graph other than a histogram that shows the distribution of a quantitative variable in a newspaper, a magazine, or the Internet.1. Does the article identify the W’s?2. Discuss whether the display is appropriate for the data.3. Discuss what the display reveals about the
Cartoons You’ll find a number of cartoons throughout this text. Are they Are cartoons simply entertaining, or will they help with learning? Lawrence M. Lesser, Dennis K. Pearl, and John J. Weber III (“Assessing fun items’ effectiveness in increasing learning of college introductory statistics
Centers in the news Find an article in a newspaper, a magazine, or the Internet that discusses an “average.”1. Does the article discuss the W’s for the data?2. What are the units of the variable?3. Is the average used the median or the mean? How can you tell?4. Is the choice of median or mean
Spreads in the news Find an article in a newspaper, a magazine, or the Internet that discusses a measure of spread.1. Does the article discuss the W’s for the data?2. What are the units of the variable?3. Does the article use the range, IQR, or standard deviation?4. Is the choice of measure of
Tables in the news Find a contingency table of categorical data from a newspaper, a magazine, or the Internet.1. Is it clearly labeled?2. Does it display percentages or counts?3. Does the accompanying article tell the W’s of the variables?4. Do you think the article correctly interprets the data?
Graphs in the news Find a bar graph or pie chart of categorical data from a newspaper, a magazine, or the Internet.1. Is the graph clearly labeled?2. Does the graph violate the area principle?3. Does the accompanying article tell the W’s of the variable?4. Do you think the article correctly
In the news Find an article in a newspaper, a magazine, or the Internet that compares two or more groups of data.1. Does the article discuss the W’s?2. Is the chosen display appropriate? Explain.3. Discuss what the display reveals about the groups.4. Does the article accurately describe and
Groups on the Internet Find data on the Internet (or elsewhere) for two or more groups. Make appropriate displays to compare the groups, and interpret what you find.
Incomes The mean household income in the U.S. in 2014 was about $72,641 and the standard deviation was about $85,000. (The median income was $51,939.) If we used the Normal model for these incomes,1. What would be the household income of the top 1%?2. How confident are you in the answer in part
IQ, finis Consider the IQ model N(100,15) one last time.a. What IQ represents the 15th percentile?b. What IQ represents the 98th percentile?c. What’s the IQR of the IQs?
ACT scores The Mathematics section of the ACT test had a mean of 20.9 and an SD of 5.3 for the years 2013–2015. If these are well modeled by a Normal distribution, about what percent of students scoreda. Over 31?b. Under 18?c. Between 18 and 31?
Dexterity scores Scores on a test of dexterity are recorded by timing a subject who is inverting pegs by picking them up with one hand, manipulating them to turn them over, and then placing them back in a frame. A typical 4-year-old needs about 3.125 seconds to invert a peg, but a 9-year-old takes
Prediction units The errors in predicting hurricane tracks (examined in this chapter) were given in nautical miles. A statutory mile is 0.86898 nautical mile. Most people living on the Gulf Coast of the United States would prefer to know the prediction errors in statutory miles rather than nautical
More predictions Hurricane Katrina’s hurricane force winds extended 120 miles from its center. Katrina was a big storm, and that affects how we think about the prediction errors. Suppose we add 120 miles to each error to get an idea of how far from the predicted track we might still find damaging
More regression equations Fill in the missing information in the following table. x sx y syr y^=b0+b1x a) 30 4 18 6 -0.2 b) 100 18 60 10 -0.9 0.8 50 15 c) d) y^= -10+15x 18 4 -0.6 y^-30-2x
Cereal again The correlation between a cereal’s fiber and potassium contents is r=0.903. What fraction of the variability in potassium is accounted for by the amount of fiber that servings contain?
Another car The correlation between a car’s engine size and its fuel economy (in mpg) is r=−0.774. What fraction of the variability in fuel economy is accounted for by the engine size?
Abalone Abalones are edible sea snails that include over 100 species. A researcher is working with a model that uses the number of rings in an abalone’s shell to predict its age. He finds an observation that he believes has been miscalculated. After deleting this outlier, he redoes the
Stopping times Using data from 20 compact cars, a consumer group develops a model that predicts the stopping time for a vehicle by using its weight. You consider using this model to predict the stopping time for your large SUV. Explain why this is not advisable.
Cell phone costs Noting a recent study predicting the increase in cell phone costs, a friend remarks that by the time he’s a grandfather, no one will be able to afford a cell phone. Explain where his thinking went awry.
Skinned knees There is a strong correlation between the temperature and the number of skinned knees on playgrounds. Does this tell us that warm weather causes children to trip?
Cell phones and life expectancy The correlation between cell phone usage and life expectancy is very high. Should we buy cell phones to help people live longer?
Grading A team of calculus teachers is analyzing student scores on a final exam compared to the midterm scores. One teacher proposes that they already have every teacher’s class averages and they should just work with those averages. Explain why this is problematic.
Average GPA An athletic director proudly states that he has used the average GPAs of the university’s sports teams and is predicting a high graduation rate for the teams. Why is this method unsafe?
Baseball salaries 2015 Ballplayers have been signing ever-larger contracts. The highest salaries (in millions of dollars per season) for each year since 1874 are in the data file Baseball salaries 2015.a. Make a scatterplot of Adjusted salary vs. Year. Does it look straight?b. Find the best
The Internet Find an Internet source that reports on a study and describes the data. Print out the description and identify as many of the W’s as you can.
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