Periodically, some researchers test the hypothesis that cell phones can cause a cancer in those who use them. In one such study, it was found that among 420,095 cell phone users, 135 developed cancer of the brain or nervous system.
> 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?
> What percentage of adult males have pulse rates greater than 53 bpm?
> In 1965, Intel cofounder Gordon Moore initiated what has since become known as Moore’s law: The number of transistors per square inch on integrated circuits will double approximately every 18 months. In the table below, the first and th
> What is the standard score (z-score) corresponding to the pulse rate of 53 bpm for an adult male?
> Samples of 36 adult males are randomly selected and the mean is found for each sample. What is the standard deviation of the sample means?
> Samples of 36 adult males are randomly selected and the mean is found for each sample. What is the mean of the sample means?
> Use Table A-1 to find the percentage of pulse rates of adult men between 60 and 80 bpm.
> Using the 68-95-99.7 rule, find the percentage of pulse rates of adult men between 48 and 92 bpm.
> Which of the following is likely to have a distribution that is closest to a normal distribution? a. The outcomes that occur when a single die is rolled many times b. The outcomes that occur when two dice are rolled many times and the mean is computed ea
> What percentage of adult males have pulse rates between 59 and 92 bpm?
> Which of the following statements are correct? a. A normal distribution is any distribution that typically occurs. b. The graph of a normal distribution is bell-shaped. c. The graph of a normal distribution always has one mode. d. In a normal distributio
> Which of the following statistics would be best for monitoring the consistency of the weights of Dunkin’ Donuts regular doughnuts: mean, median, mode, range, standard deviation?
> The pie charts in Figure 3.38 give the percentages of Americans in three age categories in 1990 and 2050 (projected). a. Consider the 1990 age distribution. The actual percentages for the three categories for 1990 were 87.5% (others), 11.3% (60â
> Which of the following statements could apply to a data set consisting of 1000 values that are all deferent? a. The 20th percentile is greater than the 30th percentile. b. The median is greater than the first quartile. c. The third quartile is greater th
> A histogram is constructed for a large set of pulse rates of adult males, and it is found that the distribution is symmetric and unimodal. What does this imply about the values of the mean and median?
> Find the standard deviation of these earthquake magnitudes: 2.99, 2.58, 2.44, 2.91, and 3.38.
> Use the range rule of thumb to estimate the standard deviation of the earthquake magnitudes given in Exercise 1. How close is the result to the actual standard deviation of 0.999?
> The standard deviation of the magnitudes given in Exercise 1 is 0.999. What characteristic does that value measure?
> What is the range of the magnitudes given in Exercise 1?
> Nine-year-old Emily Rosa became an author of an article in the Journal of the American Medical Association after she tested professional touch therapists (see “Focus on Education” in Chapter 10). Using a cardboard partition, she held her hand above the t
> Find the median of the magnitudes given in Exercise 1.
> Identify the names of the components that constitute the five number Summary for a data set.
> When you add the earthquake magnitudes 2.45, 3.62, 3.06, 3.30, and 1.09, then divide by the number of values, the result is 2.704. Which term best describes this value: average, mean, median, mode, or standard deviation?
> Refer to Figure 3.37 in Exercise 15 and construct a bar chart to depict the same data in a way that is fair and objective. Figure 3.37
> When constructing a graph of the same categorical data, why is a Pareto chart generally better than a pie chart?
> In 1986, the subway fare in New York City was $1, and the fare in 2015 was $2.50. In Figure 3.45, the bill representing the 2015 fare is 2.5 times as tall and 2.5 times as wide as the bill representing the 1986 fare. Does the graphic convey the actual ch
> The third category in a frequency table has a cumulative frequency of 95. What does the value of 95 indicate?
> The first category in a relative frequency table is 90–100, and the corresponding relative frequency is 0.18. What does the value of 0.18 indicate?
> The first category in a frequency table is 90–100, and the corresponding frequency is 76. What does the value of 76 indicate?
> A dot plot of braking distances (in feet) of cars is constructed, and a portion of the dot plot is shown below. Identify the values represented in this dot plot. Figure 3.44
> A stem plot is created with the braking distances (in feet) of cars, and one row of that stem plot is 14 | 000335. Identify the values represented by that row.
> In a study of the effects of magnets on back pain, some subjects were treated with magnets while others were given non-magnetic devices with a similar appearance. The magnets did not appear to be effective in treating back pain (Journal of the American M
> As a quality control manager at Ford, you monitor the time it takes to manufacture each new Taurus car. Which of the following graphs would be best for displaying those times: histogram, bar graph, Pareto chart, dot plot, or pie chart?
> Why are pictographs generally poor for depicting one- dimensional data, such as consumption of oranges in different years?
> Figure 3.37 depicts the amounts of daily oil consumption (in millions of barrels) in the United States and Japan. Does the illustration accurately depict the data? Why or why not? Figure 3.37
> Listed below are body temperatures (in °F) of healthy adults. Why would a graph of these data not be very effective in helping us understand them? 98.6 98.6 98.0 98.0 99.0 98.4 98.4 98.4 98.4 98.6 Answer: The data set is too small for a graph to revea
> As a quality control manager at Ford Motor Company, you find that repairs needed on new cars have various causes, including software, human error, and worn machinery. Which graph would be most appropriate for these data: histogram, bar graph, Pareto char
> The Telektronics Company has been in business for five years, and the following table lists the company’s net profit in each of those years. Using the first year as a reference value, find the index number for the net profit in the seco
> Two different students measure the height of an instructor who is actually 178.44 cm tall. The first student obtains a measurement of 178 cm and the second student obtains a measurement of 179.18 cm. Which measurement is more accurate? Which measurement
> In a Gallup poll of 1038 adults, 5% of the respondents said that second-hand smoke is not at all harmful. How many respondents said that second-hand smoke is not at all harmful?
> Recorded survey results include the states in which respondents reside. Are those data considered quantitative or qualitative, and what is their level of measurement (nominal, ordinal, interval, or ratio)?
> Braking reaction times of 36 randomly selected licensed drivers are measured and 20 of them are greater than 1.9 seconds. What is the percentage of reaction times greater than 1.9 seconds?
> A researcher measures the braking reaction time of a subject and records a value of 2.4 seconds, but the subject’s actual braking reaction time is 1.9 seconds. What is the relative error?
> Tempered glass is used for car windows because it is much tougher than regular glass. A researcher tests the strength of samples of glass by heating them at 620°C, which is the industry standard.
> A researcher measures the braking reaction time of a subject and records a value of 2.4 seconds, but the subject’s actual braking reaction time is 1.9 seconds. What is the absolute error?
> You want to conduct a survey of parents of elementary school students in Minneapolis by using telephone calls instead of personal visits. Assume you have directories listing telephone numbers of all (or almost all) parents at each of the city’s elementar
> What is the level of measurement of the values described in Exercise 1 (nominal, ordinal, interval, or ratio)?
> Refer to the table in Exercise 9. If the net profit in the sixth year is projected to be 5% less than the net profit in the fifth year, what is that projected sixth-year net profit?
> Braking reaction times of 36 randomly selected licensed drivers are measured. Are those data considered quantitative or qualitative? If quantitative, are those values continuous or discrete?
> If a statistical study is carefully conducted in every possible way, then: (a) Its results must be correct; (b) We can have confidence in its results, but it is still possible that the results are not correct; (c) We say that the study is perfectly biase
> Consider a survey of randomly selected people in which it is found that participants who used sunscreen were more likely to have been sunburned in the past year. Which explanation for this result seems most likely? (a) Sunscreen is useless; (b) The peop
> Consider a study in which you measure the weights of dolphins. The variable of interest in this study is: (a) The size of the sample; (b) The weights of dolphins; (c) The average (mean) weight of all dolphins.
> From the poll results given in Exercise 11, can we safely conclude that the majority of people are most annoyed by the use of “whatever” in conversation?
> In a Marist Poll, respondents chose the most annoying phrases used in conversation. Among the 864 subjects who were surveyed, 51% chose “whatever.” The survey has a margin of error of 3 percentage points. Identify the range of values for the confidence i
> If all subjects in the aspirin treatment group are athletes and all subjects in the control group are not athletes, then there is a danger of which of the following: (a) Samples those are too small; (b) Confounding; (c) Blinding.
> The Nielsen Company installs devices in homes to record the TV shows that are watched. The results are then used to provide ratings identifying which shows are being viewed more than others.
> Figure 3.36 on the next page depicts the annual high values of the Dow Jones Industrial Average (DJIA) for stocks. How is this graph misleading? How could it be drawn so that it is not misleading? In this case, would the graph change dramatically if it w
> In a Gallup poll of 1018 adults, it was found that 22% smoked cigarettes in the past week.
> If we see a placebo effect, it means: (a) The experiment was not really double-blind; (b) The experimental groups were too small; (c) Pulse rates were lowered among some of those in the placebo group.
