In a survey of 703 randomly selected workers, 429 got their jobs through networking (based on data from Taylor Nelson Sofres Research). a. Use the sample data with a 0.05 significance level to test the claim that most (more than 50% of) workers get their jobs through networking. b. If given a claim that less than 50% of workers get their jobs through networking, why is it not necessary to go through the steps of conducting a formal hypothesis test? What should we conclude?
> Is it possible for a graph that shows percentage change to show descending bars (or a descending line) even when the variable of interest is increasing? Explain.
> A sample of manufactured air bags is obtained by using a computer to randomly generate a number between 1 and 1000 for each air bag, and the air bag is tested if the generated number is 1000.
> Waiting times (in minutes) of customers at the Jefferson Valley Bank (where all customers enter a single waiting line) and the Bank of Providence (where customers wait in individual lines at three different teller windows) are listed below. Determine whe
> Listed below are randomly selected contributions (in dollars) made to the two presidential candidates in a recent election. All contributions are from the same ZIP code. (The data are from the Huffington Post.) Do the contributions appear to favor either
> An educational researcher conducted a census to determine the average (mean) number of years it takes undergraduate statistics students to earn a college degree.
> Listed below are amounts (in millions of dollars) collected from parking meters by Brinks and others in New York City during similar time periods. A larger data set was used to convict five Brinks employees of grand larceny. (The data were provided by th
> Listed below are speeds (in mi/h) of cars on the New Jersey Turnpike, where the speed limit is 65 mi/h. All cars are going in the same direction, and all of the cars are from New Jersey. The speeds were measured with a radar gun, and the researchers obse
> Suppose you have scores of 60, 70, 65, 85, and 85 on exams in a sociology class. a. What is the mean of these scores? b. What score would you need on the next exam to have an overall mean of 75? c. If the maximum score on an exam is 100, what is the maxi
> Suppose you have scores of 80, 84, 87, and 89 on quizzes in a mathematics class. a. What is the mean of these scores? b. What score would you need on the fifth quiz to have an overall mean of 88? c. If the maximum score on a quiz is 100, is it possible t
> The contents of cans of regular Coca-Cola vary slightly in weight. Here are the measured weights of seven cans, in pounds: 0.8161 0.8194 0.8165 0.8176 0.7901 0.8143 0.8126 a. Find the mean and median of these weights. b. Which, if any, of these weights
> The states of Alabama, Alaska, Arizona, Arkansas, California, Colorado, and Connecticut have the following areas in square miles (land and water), with the areas listed in the same order as the states: 52,200 615,200 114,000 53,200 158,900 104,
> What is an exponential scale, and when is such a scale useful?
> Listed below are measurements of specific absorption rate (SAR) of radiation (in W/kg) when these types of cell phones are held to the head: Samsung SGHtss9, Blackberry Storm, Blackberry Curve, Motorola Moto, T-Mobile Sidekick, Sanyo Katana Eclipse, Palm
> What is a distribution of data? Describe the important labels we should include when making a graph of a distribution.
> Below are measurements of blood alcohol concentration (BAC) for randomly selected drunk drivers involved in fatal crashes and then given jail sentences (based on data from the U.S. Department of Justice). Are these data consistent with laws stating that
> Below are body temperatures (in °F) of randomly selected normal, healthy adults. What do the results suggest about “normal” body temperature? 98.6 ………98.6 ………98.0 ………98.0 ………99.0 98.4 ………98.4 ………98.4 ………98.4 ………98.6
> The data below are times (in seconds) recorded when statistics students participated in an experiment to test their ability to determine when 1 minute (60 seconds) had passed. What do these data suggest about students’ perception of time? 53 …………52 …………7
> List and define five common sampling methods. Give an example of each.
> A pollster plans to improve survey results by only conducting polls in which the margin of error is zero.
> Listed below are the numbers on the jerseys of the starting lineup for the New Orleans Saints when they won their first Super Bowl football game. Are the mean, median, and mode for these data meaningful? 9 ……23 ……25 ………88 …………12 …………19 …………74 …………77 …………
> Ayurveda is a traditional medical system commonly used in India. Listed below are the lead concentrations (in °g/g) measured in different Ayurveda medicines (manufactured in the United States). (Data from “Lead, Mercury, and Arsenic in U.S. and Indian Ma
> Listed below are measurements of the “head injury criterion (hic)” for seven small cars tested in crashes by the National Highway Traffic Safety Administration: Chevrolet Aveo, Honda Civic, Volvo S40, VW Jetta, Hyundai Elantra, Kia Rio, and Kia Spectra.
> A professional driver is used to compare the handling of Ford Taurus cars and Porsche 911 cars.
> In a test of the effects of lifting heavy weights on blood pressure, one group undergoes a treatment consisting of a weight-lifting program, while another group lifts tennis balls.
> You want to determine the average (mean) error of aircraft altimeters when they are tested at a simulated altitude of 1000 feet.
> In a clinical trial of the effectiveness of a lotion used to treat tinea pedis (athlete’s foot), the physicians who evaluate the results know which subjects were given the treatment and which were given a placebo.
> The Journal of Consumer Research included a report of a study that was conducted to determine whether people have different spending characteristics when they have a $1 bill or when they have four quarters. The subjects were given a choice: keeping the m
> In one of Mendel’s famous genetics experiments that he conducted with peas, he obtained a sample of offspring peas consisting of 428 green peas and 152 yellow peas. Based on his theories, he expected that 25% of the offspring peas would be yellow.
> In a comparison of gasoline with different octane ratings, 24 vans are driven with 87 octane gasoline, and 28 sport utility vehicles are driven with 91 octane gasoline. After each vehicle has been driven for 250 miles, the amount of gasoline it consumed
> An experiment conducted at Pennsylvania State University was designed to evaluate the effects of irrigation and fertilizers on poplar tree growth. Two different sites were used: (1) rich and moist; (2) sandy and dry. Each of the two sites was partitioned
> An experiment conducted at Pennsylvania State University was designed to evaluate the effectiveness of irrigation and fertilizers on poplar tree growth. Fertilizer is used with one group of poplar trees in a moist region, and irrigation is used with popu
> Results were combined from ten major studies involving a total of more than 1.25 million children. The analysis confirmed that there is no linkage between vaccines and autism (Vaccine, Volume 32, Issue 29, pages 3623–3629).
> What is a margin of error, and how is it used to establish a confidence interval? What is the confidence interval used for?
> Hundreds of separate and individual scientific and statistical studies have been done to determine whether high-voltage overhead power lines increase the incidence of cancer among those living nearby. A summary study based on many previous studies conclu
> For 186 randomly selected babies, the average (mean) of their birth weights is 3103 grams (based on data from “Cognitive Outcomes of Preschool Children with Prenatal Cocaine Exposure,” by Singer et al., Journal of the American Medical Association, Vol. 2
> Should the vertical scale on a graph showing changes in number (or percentage) with time always start from a value of zero? Why or why not?
> Define the terms population, population parameter, sample, raw data, and sample statistic as they apply to statistical studies.
> State the two different meanings of the term statistics.
> In a survey of 3005 adults aged 57 through 85 years; it was found that 82% of them used at least one prescription medication (Journal of the American Medical Association). The margin of error is 1 percentage point. a. Interpret the margin of error by id
> In The Superpollsters, David W. Moore describes an experiment in which different subjects were asked if they agree with the following statements: i. Too little money is being spent on welfare. ii. Too little money is being spent on assistance to the po
> Rhinoviruses typically cause common colds. In a test of the effectiveness of echinacea in preventing rhinovirus infections, 40 of the 45 subjects treated with echinacea developed such infections. a. Based on the given information, can you conclude that
> An important element of this chapter is the concept of a simple random sample. a. What is a simple random sample? b. When the Bureau of Labor Statistics conducts a survey, it begins by partitioning the U.S. adult population into 2007 groups called prim
> The following table lists the federal hourly minimum wage in both actual dollars at the time and 2012 dollars (based on data from the U.S. Department of Labor). a. According to the table, how much is $0.25 in 1938 dollars worth in 2012 dollars? b. Accord
> a. If a typical adult female has a pulse rate that is 6% higher than that of a typical adult male, then the typical adult female’s pulse rate is _____ of the typical adult male’s pulse rate. b. A female has a pulse rate of 80 beats per minute and her bro
> Total spending on health care in the United States rose from $80 billion in 1973 to $3.0 trillion in 2014. The Consumer Price Index was 44.4 in 1973, and it was 236.7 in 2014 (with 1982–1984 100). Compare the change in health care spending from 1973 to
> In a Wakefield Research survey, 1003 subjects were asked if they ever hesitated to give a handshake because of a fear of germs. Of these respondents, 41.0% answered “yes.” a. What is the number of respondents who answered “yes”? b. If 24 of the responden
> Use a ruler to measure the lengths of the two dollar bills in Figure 3.29. Do the lengths accurately reflect the change in value? In what way is the graphic potentially misleading? Figure 3.29
> In a Harris Interactive survey of 1006 randomly selected subjects, 96% of adults said that they wash their hands in public restrooms.
> A medical student wants to test the claim that males who smoke have pulse rates with a mean greater than 70. She collects sample data by surveying her fellow medical students. What is the fundamental flaw in this procedure?
> In a study of smokers who tried to quit smoking with nicotine patch therapy, 39 were smoking one year after the treatment, and 32 were not smoking one year after the treatment (based on data from “High Dose Nicotine Patch Therapy,” by Dale et al., Journa
> A random sample of 40 quarters minted after 1964 are weighed. The mean weight is 5.639 grams and the standard deviation is 0.062 gram. Assume that we want to use a 0.05 significance level to test the claim that the population of quarters has a mean weigh
> a. You have been hired by Intel to determine the proportion of computer owners who plan to upgrade to a new operating system. Assuming that you want to be 95% confident that your sample proportion is within 0.02 of the true population proportion, how man
> A sample of 40 randomly selected women is obtained, and the blood platelet count (in thousands of platelets per microliter of blood) of each subject is measured. The mean blood platelet count is 279.5 and the standard deviation is 65.2. a. Use these samp
> We want to estimate the mean IQ score for the population of college students. We know that for people randomly selected from the general population, the standard deviation of IQ scores is 15. a. Using a standard deviation of 15, how many college students
> One of Mendel’s famous genetics experiments yielded 580peas, with 428 of them green and 152 yellow. a. What single value is the best estimate of the population proportion of yellow peas? b. Use the sample results to construct a 95% confidence interval f
> Assume that body temperatures of healthy adults are normally distributed with a mean of 98.20F and a standard deviation of 0.62F (based on data from University of Maryland researchers). a. If you have a body temperature of 99.00F, what is your percentile
> The graph in Figure 3.42 shows simultaneously the number of births in the United States during two time periods: 1946–1964 and 1977–1994. When did the first baby boom peak? When did the second baby boom peak? Why do yo
> Women have head circumferences that are normally distributed with a mean of 22.65 inches and a standard deviation of 0.80 inch. a) Using the 68-95-99.7 rule, find the percentage of women with head circumferences that are within 0.80 inch of the mean of 2
> Researchers created a form of genetically modified corn and compared it to nonmodified corn, looking for differences in the substances released into the soil from the corn roots.
> For each of the following situations, state whether the distribution of values is likely to be a normal distribution. Give a brief explanation justifying your choice. a. Numbers resulting from spins of a roulette wheel. (There are 38 equally likely slots
> a. What is the standard deviation for a data set of 50 values, all of which are the same? b. Which of the following two car batteries would you prefer to buy, and why? One taken from a population with a mean lifetime of 48 months and a standard deviatio
> Combine the two data sets from Review Exercise 1 and find the following: a. The mode b. The percentile for 20 chocolate chips
> Listed below are counts of the numbers of chocolate chips in two different types of cookies. a. Find the mean and median for each of the two data sets. b. Find the range and standard deviation for each of the two data sets. c. Use the same scale to con
> USA Today reported these annual amounts spent in the United States for different categories of sports equipment: fishing ($2.0 billion); hunting ($3.1 billion); camping ($1.7 billion); golf ($2.5 billion). Construct a pie chart depicting these data.
> Listed below are measured weights (in pounds) of the contents in samples of cans of regular Pepsi and Diet Pepsi. Regular Pepsi 0.8258 …………0.8156…â&
> Listed below are measured weights (in pounds) of the contents in samples of cans of regular Pepsi and Diet Pepsi. Regular Pepsi 0.8258 ………… 0.8156 ………… 0.8211 ………… 0.8170 …………0.8216 …………0.8302 0.8192 ………… 0.8192 …………0.8271 …………0.8251 …………0.8227 …………0.82
> Listed below are measured weights (in pounds) of the contents in samples of cans of regular Pepsi and Diet Pepsi. Regular Pepsi 0.8258 ………… 0.8156 …………0.8211 ………… 0.8170 …………0.8216 …………0.8302 0.8192 …………0.8192 …………0.8271 …………0.8251 …………0.8227 …………0.825
> The graph in Figure 3.41 shows the federal minimum wage in the United States, together with its purchasing power, which is adjusted for inflation, with 1996 used as the reference year. The graph represents the years from 1955 to 2015. Summarize what the
> Listed below (in order by row) are annual high values of the Dow Jones Industrial Average from 1995 through 2015. Construct a time-series line chart of the data. Comment on the result. 5,216 6,561 8,259 9,374 11,568 11,401 11,350 10,635 10,454 10,855 10,
> Figure 3.43 shows the numbers of U.S. adoptions from other countries in the years 2004 and 2015. What is wrong with this graph? Draw a graph that depicts the data in a fair and objective way.
> Construct a Pareto chart from the data given in Exercise 4. Compare the Pareto chart to the pie chart. Which graph is more effective in showing the amounts spent on the different categories? Explain.
> In a 3M Privacy Filters poll, 1002 adults were asked to identify their favorite seats when they fly, and 492 of them chose a window seat.
> Suppose that 5% of the 500 survey participants use “password.” Is the value of 5% a sample statistic or a population parameter?
> What method of sampling is used if 10 Internet users are randomly selected from each of the 50 states?
> Identify the population and the sample.
> What are the two possible conclusions that can be reached about the claim being tested?
> What are the two possible conclusions that can be reached about the null hypothesis?
> If the hypothesis test results in a P-value of 0.100, what do you conclude about the given claim?
> What is the alternative hypothesis?
> The graph in Figure 3.40 on the next page shows data regarding the relative risk of schizophrenia among people born in different months. a. Note that the scale of the vertical axis does not start at zero. What would be the effect of sketching the same ri
> What is the null hypothesis?
> Is a test of the claim that p ≠ 0.75 left-tailed, right-tailed, or two-tailed?
> Identify the null and alternative hypotheses for testing the claim that the proportion of convicted felons who serve time in prison is equal to 0.6.
> In a study of the XSORT gender selection method developed by the Genetics & IVF Institute, 945 couples given treatment had 66 baby boys and 879 baby girls.
> Identify the null and alternate hypotheses for testing the claim that the proportion of college graduates who got a job within one month of graduation is greater than 0.4.
> If you incorrectly conclude that Google employees have a mean IQ score greater than 115 when their actual mean IQ score is equal to 115, have you made a type I error or a type II error?
> Identify the null and alternative hypotheses for testing the claim that the mean annual income of college graduates is greater than $35,000.
> When a 95% confidence interval is constructed for a population mean, the sample mean is found to be 68.2 cm and the margin of error is found to be 5.8 cm. Identify the 95% confidence interval.
> When a 95% confidence interval is constructed for a population proportion, the sample proportion is found to be 0.656 and the margin of error is found to be 0.120. Identify the 95% confidence interval.
> Find the margin of error and sample mean corresponding to this 95% confidence interval: 98.0 < µ < 98.6.
> The graph in Figure 3.39 shows the percentage change in the Consumer Price Index (CPI) over recent years. In what year (of the years displayed) was the change in the CPI the greatest? What happened in 2009? How did actual prices in 2015 compare to those
> A random sample of 235 females and 240 males is obtained for a clinical trial. Construct a 95% confidence interval to estimate the proportion of females in all such samples.
> Assume that we want to estimate the mean annual income of adult males in the United States. If a random sample of annual incomes of adult males is obtained, which of the following is the best estimate of the population mean? a. Median of the sample b. Me
> A journal article provides a confidence interval for a proportion in the format 0.35 {0.05. Express this confidence interval in the format a < p̂ < b. (That is, rewrite a < p < b using specific values in place of a and b.)
> What do the notations x ‾ and p̂ represent? Why are they important?
> A study of 2500 fatal car crashes identified those that involved drivers who were texting and those who were not.
> If many different random samples of size 100 are selected from the population of voters, what is the shape of the distribution of the sample proportions of registered Republicans?
> Identify what is wrong with this 95% confidence interval for a population proportion: $250 < p < $500.
> If many different random samples of size 100 are selected from the population of weights of adult dolphins, what is the shape of the distribution of the sample means?
> What percentage of adult males have pulse rates less than 81 bpm?
