A swimsuit manufacturer wants to test the speed of its newly designed suit. The company designs an experiment by having 6 randomly selected Olympic swimmers swim as fast as they can with their old swimsuit first and then swim the same event again with the new, expensive swimsuit. The company will use the difference in times as the response variable. Criticize the experiment and point out some of the problems with generalizing the results.
> Here are the number of domestic f lights flown in each year from 2000 to 2016 (www.transtats.bts.gov/homepage.asp): a) Find the correlation of Flights with Year. b) Make a scatterplot and describe the trend. c) Why is the correlation you found in part
> Laptop computers have been growing in popularity according to a study by Current Analysis Inc. Laptops now represent more than half the computer sales in the United States. A campus bookstore sells both types of computers and in the last semester sold 56
> The CEO of a mid-sized company has to relocate to another part of the country. To make it easier, the company has hired a relocation agency to help purchase a house. The CEO has 5 children and so has specified that the house have at least 5 bedrooms, but
> A business student is searching for a used car to purchase, so she posts an ad to a website saying she wants to buy a used Jeep between $18,000 and $20,000. From Kelley’s BlueBook.com, she learns that there are 149 cars matching that de
> A cell phone manufacturer samples cell phones from the assembly to test. She noticed that the number of faulty cell phones in a production run of cell phones is usually small and that the quality of one day’s run seems to have no bearing on the next day.
> A website manager has noticed that during the evening hours, about 3 people per minute check out from their shopping cart and make an online purchase. She believes that each purchase is independent of the others. a) What model might you suggest to model
> My employee seems to leave work anytime between 5 pm and 6 pm, uniformly. a) What is the probability he will still be at work at 5:45 pm? b) What is the probability he will still be at work at 5:45 pm every day this week (M–F)? c) What did you assume
> Defects can occur anywhere on the wheel of a car during the manufacturing process. If X is the angle where the defect occurs, measured from a reference line, then X can be modeled as a uniform random variable on the interval from 0 to 360 degrees. a) Wh
> A tennis player has taken a special course to improve her serving. She thinks that individual serves are independent of each other. She has been able to make a successful first serve 70% of the time. Use a Normal approximation to find the probability she
> Vitamin D is essential for strong, healthy bones. Although the bone disease rickets was largely eliminated in England during the 1950s, some people there are concerned that this generation of children is at increased risk because they are more likely to
> Can we use probability models based on Bernoulli trials to investigate the following situations? Explain. a) Each week a doctor rolls a single die to determine which of his six office staff members gets the preferred parking space. b) A medical researc
> Police estimate that 80% of drivers wear their seatbelts. They set up a safety roadblock, stopping cars to check for seatbelt use. If they stop 120 cars, what’s the probability they find at least 20 drivers not wearing their seatbelt? Use a Normal approx
> A lecture hall has 200 seats with folding arm tablets, 30 of which are designed for left-handers. The typical size of classes that meet there is 188, and we can assume that about 13% of students are left-handed. Use a Normal approximation to find the pro
> The Atlas BodyBuilding Company (ABC) sells “starter sets” of barbells that consist of one bar, two 20-pound weights, and four 5-pound weights. The bars weigh an average of 10 pounds with a standard deviation of 0.25 pound. The weights average the specifi
> At a certain coffee shop, all the customers buy a cup of coffee; some also buy a doughnut. The shop owner believes that the number of cups he sells each day is normally distributed with a mean of 320 cups and a standard deviation of 20 cups. He also beli
> The bicycle shop in Exercise 55 estimates using current labor costs that unpacking a bike costs $0.82 on average with a standard deviation of $0.16. Assembly costs $8.00 on average with a standard deviation of $0.88 and tuning costs $4.10 with a standard
> Bicycles arrive at a bike shop in boxes. Before they can be sold, they must be unpacked, assembled, and tuned (lubricated, adjusted, etc.). Based on past experience, the shop manager makes the following assumptions about how long this may take: â&#
> You’re thinking about getting two dogs and a cat. Assume that annual veterinary expenses are independent and have a Normal model with the means and standard deviations described in Exercise 52. a) Define appropriate variables and express the total annua
> In Exercise 51 we poured a large and a small bowl of cereal from a box. Suppose the amount of cereal that the manufacturer puts in the boxes is a random variable with mean 16.2 ounces and standard deviation 0.1 ounce. a) Find the expected amount of cere
> Consider each of these situations. Do you think the proposed sampling method is appropriate? Explain. a) We want to know if business leaders in the community support the development of an “incubator” site at a vacant lot on the edge of town. We spend a d
> Consider each of these situations. Do you think the proposed sampling method is appropriate? Explain. a) We want to know what percentage of local doctors accept Medicaid patients. We call the offices of 50 doctors randomly selected from local Yellow Page
> A real-estate broker in Washington, DC, purchased 3 two-bedroom houses in a depressed market for a combined cost of $1,000,000. He expects the cleaning and repair costs on each house to average $100,000 with a standard deviation of $15,000. When he sells
> For the investment experiment of Exercise 2, identify how Control, Randomization, and Replication were used. Exercise 2: For the following experiment, identify the experimental units, the treatments, the response, and the random assignment. An investme
> Concerned about reports of discolored scales on fish caught downstream from a newly sited chemical plant, scientists set up a field station in a shoreline public park. For one week they asked fishermen there to bring any fish they caught to the field sta
> Sammy’s Salsa, a small local company, produces 20 cases of salsa a day. Each case contains 12 jars and is imprinted with a code indicating the date and batch number. To help maintain consistency, at the end of each day, Sammy selects three bottles of sal
> A manufacturing company employs 14 project managers, 48 foremen, and 377 laborers. In an effort to keep informed about any possible sources of employee discontent, management wants to conduct job satisfaction interviews with a simple random sample of emp
> A consumer group wants to test the effectiveness of a new “organic” laundry detergent and make recommendations to customers about how to best use the product. They intentionally stain 30 white T-shirts with grass in order to see how well the detergent wi
> An industrial machine requires an emergency shutoff switch that must be designed so that it can be easily operated with either hand. Design an experiment to find out whether workers will be able to deactivate the machine as quickly with their left hands
> Can special study courses actually help raise SAT scores? One organization says that the 30 students they tutored achieved an average gain of 60 points when they retook the test. a) Explain why this does not necessarily prove that the special course caus
> Hoping to learn how to control crop damage by a certain species of beetle, a researcher plans to test two different pesticides in small plots of corn. A few days after application of the chemicals, he’ll check the number of beetle larvae found on each pl
> A research doctor has discovered a new ointment that she believes will be more effective than the current medication in the treatment of shingles (a painful skin rash). Eight patients have volunteered to participate in the initial trials of this ointment
> A study published in the New England Journal of Medicine (Aug. 2001) suggests that it’s dangerous to enter a hospital on a weekend. During a 10-year period, researchers tracked over 4 million emergency admissions to hospitals in Ontario, Canada. Their fi
> Do cars get better gas mileage with premium instead of regular unleaded gasoline? It might be possible to test some engines in a laboratory, but we’d rather use real cars and real drivers in real day-to-day driving, so we get 20 volunteers. Design the ex
> A collector purchased a quantity of action figures and is going to sell them on eBay. He has 19 Hulk figures. In recent auctions, the mean selling price of similar figures has been $12.11, with a standard deviation of $1.38. He also has 13 Iron Man figur
> Some schools teach reading using phonics (the sounds made by letters) and others using whole language (word recognition). Suppose a school district wants to know which method works better. Suggest a design for an appropriate experiment.
> A medical researcher suspects that giving post-surgical patients large doses of vitamin E will speed their recovery times by helping their incisions heal more quickly. Design an experiment to test this conjecture. Be sure to identify the factors, levels,
> Before drilling for water, many rural homeowners hire a dowser (a person who claims to be able to sense the presence of underground water using a forked stick). Suppose we wish to set up an experiment to test one dowser’s ability. We get 20 identical con
> Giant food stores serves two customer segments: “Budget Shoppers” and “Foodies.” Giant sends 1000 of each type of customer one of two circulars: Deep Discounts or Gourmet Food. The r
> Verizon Wireless wants to test new package deals. They are considering offering three levels of data per month (5 Gb, 10 Gb, Unlimited) and two different international calling options (no international calling, discounted international). They randomly as
> Kraft foods wants to see whether a coupon will affect sales for macaroni and cheese. Kraft picks a single grocery store in Philadelphia in which to test two coupon types: “buy one, get one free” and “
> A small maker of video games designs a pricing experiment. They know that some teens self-identify as “gamers,” while others do not. They market a new video game to gamers and non-gamers, and they send half of each gro
> Recently, a group of adults who swim regularly for exercise were evaluated for depression. It turned out that these swimmers were less likely to be depressed than the general population. The researchers said the difference was statistically significant.
> A Danish study published in the Archives of Internal Medicine casts significant doubt on suggestions that adults who drink wine have higher levels of “good” cholesterol and fewer heart attacks. These researchers followed a group of individuals born at a
> Contrast bath treatments use the immersion of an injured limb alternately in water of two contrasting temperatures. Those who use the method claim that it can reduce swelling. Researchers compared three treatments: (1) contrast baths and exercise, (2)
> An option to buy a stock is priced at $200. If the stock closes above 30 on May 15, the option will be worth $1000. If it closes below 20, the option will be worth nothing, and if it closes between 20 and 30 (inclusively), the option will be worth $200.
> An experiment showed that subjects fed the DASH diet were able to lower their blood pressure by an average of 6.7 points compared to a group fed a “control diet.” All meals were prepared by dietitians. a) Why were the subjects randomly assigned to the d
> The analyst who designed the experiment in Exercise 28 obtained the data, which is plotted are in the graph below. a) Is there an interaction effect that is large enough to be worrisome? b) The regional manager of the chain is having trouble interpreti
> A supermarket wants to see the effects of coupons on spending. They believe that male and female heads of households will respond differently to the coupons. The supermarket chooses 200 males and 200 females, and sends half of each group the coupon, whil
> A humor piece published in the British Medical Journal (“Parachute Use to Prevent Death and Major Trauma Related to Gravitational Challenge: Systematic Review of Randomized Control Trials,” Gordon, Smith, and Pell, BMJ, 2003:327) notes that we can’t tell
> A running-shoe manufacturer wants to test the effect of its new sprinting shoe on 100-meter dash times. The company sponsors 5 athletes who are running the 100-meter dash in the 2012 Summer Olympic games. To test the shoe, it has all 5 runners run the 10
> The boxplots display case prices (in dollars) of wine produced by wineries along three of the Finger Lakes in upstate New York. a) Is this an experiment? Explain. b) Does there seem to be evidence that prices may differ by location? Explain. 150 1
> These boxplots show the relationship between the number of cylinders in a car’s engine and its fuel economy from a study conducted by a major car manufacturer. a) Is this an experiment? Explain. b) Do the boxplots indicate that cars w
> An industrial machine requires an emergency shutoff switch that must be designed so that it can be easily operated with either hand. Design an experiment to find out whether workers will be able to deactivate the machine as quickly with their left hands
> Can special study courses actually help raise SAT scores? One organization says that the 30 students they tutored achieved an average gain of 60 points when they retook the test. a) Explain why this does not necessarily prove that the special course cau
> Mary is deciding whether to book the cheaper f light home college after her final exams, but she’s unsure when her last exam will be. She thinks there is only a 20% chance that the exam will be scheduled after the last day she can get a seat on the cheap
> A Danish study published in the Archives of Internal Medicine casts significant doubt on suggestions that adults who drink wine have higher levels of “good” cholesterol and fewer heart attacks. These researchers followed a group of individuals born at a
> The makers of Frumpies, “the breakfast of rug rats,” want to improve their marketing, so they consult you. a) They first want to know what fraction of children, ages 10 to 13, like their celery-flavored cereal. What kind of study should they perform? b
> An advertisement selling specially designed CDs of Mozart’s music specifically because they will “strengthen your mind, heal your body, and unlock your creative spirit” claims that “in Japan, a brewery actually reported that their best sake is made when
> Will listening to a Mozart piano sonata make you smarter? In a published study, Rauscher, Shaw, and Ky reported that when students were given a spatial reasoning section of a standard IQ test, those who listened to Mozart for 10 minutes improved their sc
> A swimsuit manufacturer wants to test the speed of its newly designed $550 suit. They design an experiment by having 6 randomly selected Olympic swimmers swim as fast as they can with their old swimsuit first and then swim the same event again with the n
> One member of the consumer group in Exercise 13 is concerned that the experiment will take too long and makes some suggestions to shorten it. Comment brief ly on each idea. a) Cut the runs to 8 by testing only the new detergent. Compare the results to r
> An outdoor products company wants to test a new website design where customers can get information about their favorite outdoor activity. They randomly send half of the customers coming to the website to the new design. They want to see whether the Web v
> A consumer group wants to test the efficacy of a new laundry detergent. They take 16 pieces of white cloth and stain each with the same amount of grease. They decide to try it using both hot and cold water settings and at both short and long washing time
> For each description of data in Exercises 7 to 26, identify the W’s, name the variables, specify for each variable whether its use indicates it should be treated as categorical or quantitative, and for any quantitative variable identify the units in whic
> For each description of data in Exercises 7 to 26, identify the W’s, name the variables, specify for each variable whether its use indicates it should be treated as categorical or quantitative, and for any quantitative variable identify the units in whic
> A farmer has 100 lb of apples and 50 lb of potatoes for sale. The market price for apples (per pound) each day is a random variable with a mean of 0.5 dollar and a standard deviation of 0.2 dollar. Similarly, for a pound of potatoes, the mean price is 0.
> The Lackawax River Group is interested in applying for state funds to continue their restoration and conservation of the Lackawax River, a river that has been polluted from years of industry and agricultural discharge. While they have managed to gain sig
> Green River Army Depot’s main business is the repair and refurbishment of electronics, mainly satellite and communication systems, in partnership with the Department of Defense (DOD). Recently, DOD has put a great deal of effort into continuous quality i
> Kurt Williams was about to open a new SEP IRA account and was interested in exploring various investment options. Although he had some ideas about how to invest his money, Kurt thought it best to seek the advice of a professional, so he made an appointme
> Fabrizio Rivetti is an entrepreneur who has recently started a wine importing business. While he currently has an exclusive relationship with only one premier winery in Tuscany, he is hoping to expand his importing business to include other wineries as w
> Rebekkah Greene, owner of Up with Life Café and Marketplace, is a true believer in the health and healing benefits of food. She offers her customers pure, wholesome, and locally sourced products. Recently, she decided to add a line of hearty “made to ord
> Beth Tully owns Zenna’s Café, an independent coffee shop located in a small Midwestern city. Since opening Zenna’s in 2002, she has been steadily growing her business and now distributes her custom coffee blends to a number of regional restaurants and ma
> Mount Ashland Promotions Inc. is organizing one of its most popular events, the ZenNaturals Annual Trade Fest. At this trade show, producers, manufacturers, and distributors in the natural foods market display the latest trends in organic foods, herbal s
> Sarah Potterman, a doctoral student in educational psychology, is researching the effectiveness of various interventions recommended to help children with learning disabilities improve their reading skills. One particularly intriguing approach is an inte
> Jim Hopler is operations manager for a local office of a top-ranked full-service brokerage firm. With increasing competition from both discount and online brokers, Jim’s firm has redirected attention to attaining exceptional customer service through its
> A large U.S. multinational that provides field services to energy companies worldwide operates in approximately 50 countries and employs nearly 85,000 people. While very profitable, this company has had its share of controversies. The most publicized inv
> A bicycle shop plans to offer 2 specially priced children’s models at a sidewalk sale. The basic model will return a profit of $120 and the deluxe model $150. Past experience indicates that sales of the basic model will have a mean of 5.4 bikes with a st
> For each description of data in Exercises 7 to 26, identify the W’s, name the variables, specify for each variable whether its use indicates it should be treated as categorical or quantitative, and for any quantitative variable identify the units in whic
> For each description of data in Exercises 7 to 26, identify the W’s, name the variables, specify for each variable whether its use indicates it should be treated as categorical or quantitative, and for any quantitative variable identify the units in whic
> Philanthropic organizations often rely on contributions from individuals to finance the work that they do, and a national veterans’ organization is no exception. The Paralyzed Veterans of America (PVA) was founded as a congressionally chartered veterans’
> A global survey firm reports data from surveys taken in several countries. The data file Global holds data for 800 respondents in each of five countries. The variables provide demographic information (sex, age, education, marital status) and responses to
> Both drivers and auto companies are motivated to raise the fuel efficiency of cars. Recent information posted by the U.S. government proposes some simple ways to increase fuel efficiency (see www.fueleconomy.gov): avoid rapid acceleration, avoid driving
> In Chapter 1, you identified the W’s for the data in the file Credit card bank. For the categorical variables in the data set, create frequency tables, bar charts, and pie charts using your software. What might the bank want to know about these variables
> Like all credit and charge card companies, this company makes money on each of its cardholders’ transactions. Thus, its profitability is directly linked to card usage. To increase customer spending on its cards, the company sends many different offers to
> The S&P/Case-Shiller Home Price Indices track changes in the value of residential real estate nationally and in 20 metropolitan regions. (Some of these indices are actually traded on the Chicago Mercantile Exchange.) The data set Case-Shiller by City giv
> According to the U.S. Securities and Exchange Commission (SEC), a mutual fund is a professionally managed collection of investments for a group of investors in stocks, bonds, and other securities. The fund manager manages the investment portfolio and tra
> GfK Roper Consulting conducts market research for multinational companies who want to understand attitudes in different countries so they can market and advertise more effectively to different cultures. Every year they conduct a poll worldwide, which ask
> At a casino, people play the slot machines in hopes of hitting the jackpot, but most of the time, they lose their money. A certain machine pays out an average of $0.92 (for every dollar played), with a standard deviation of $120. a) Why is the standard
> A young entrepreneur has just raised $30,000 from investors, and she would like to invest it while she continues her fund-raising in hopes of starting her company one year from now. She wants to do due diligence and understand the risk of each of her inv
> Design, carry out, and analyze your own multifactor experiment. The experiment doesn’t have to involve human subjects. In fact, an experiment designed to find the best settings for microwave popcorn, the best paper airplane design, or the optimal weight
> You are part of a marketing team that needs to research the potential of a new product. Your team decides to e-mail an interactive survey to a random sample of consumers. Write a short questionnaire that will generate the information you need about the n
> The Numbeo website (www.numbeo.com) provides access to a variety of data. One table lists prices of certain items in selected cities around the world. They also report an overall cost-of-living index for each city compared to the costs of hundreds of ite
> The CAPE10 index is based on the Price/Earnings (P/E) ratios of stocks. We can examine the P/E ratios without applying the smoothing techniques used to find the CAPE10. The file CAPE10 2017 holds the data, giving dates, various economic variables, CAPE10
> Between quarterly audits, a company likes to check on its accounting procedures to address any problems before they become serious. The accounting staff processes payments on about 120 orders each day. The next day, the supervisor rechecks 10 of the tran
> Occasionally, when I fill my car with gas, I figure out how many miles per gallon my car got. I wrote down those results after six fill-ups in the past few months. Overall, it appears my car gets 28.8 miles per gallon. a) What statistic have I calculate
> How much change do you have on you right now? Go ahead, count it. a) How much change do you have? b) Suppose you check on your change every day for a week as you head for lunch and average the results. What parameter would this average estimate? c) Su
> What about drawing a random sample only from cell phone exchanges? Discuss the advantages and disadvantages of such a sampling method compared with surveying randomly generated telephone numbers from non–cell phone exchanges. Do you think these advantage
> Anytime we conduct a survey, we must take care to avoid undercoverage. Suppose we plan to select 500 names from the city phone book, call their homes between noon and 4 p.m., and interview whoever answers, anticipating contacts with at least 200 people.
> Suppose that the appliance shop in Exercise 23 plans an 8-hour day. a) Find the mean and standard deviation of the number of repair calls they should expect in a day. b) What assumption did you make about the repair calls? c) Use the mean and standard
> Examine each of the following questions for possible bias. If you think the question is biased, indicate how and propose a better question. a) Do you think that price or quality is more important in selecting a tablet computer? b) Given humanity’s grea
