Properties of the standard deviation (a) Juan says that,

Marital status In the Statistical Abstract of the United States we fi nd these data on the marital status of adult American women as of 2007: Marital status Count (thousands) Never married 25,262 Married 65,128 Widowed 11,208 Divorced 13,210 Total 114,807 (a) How many women were not married in 2007? (b) Make a bar graph to show the distribution of marital status. (c) Would it also be correct to use a pie chart? If so, make a pie chart for these data.

Consistency? Refer to the previous exercise. What is the sum of the counts for the four marital status categories? Why is this sum not equal to the total given in the table?

College freshmen A survey of college freshmen asked what fi eld they planned to study. Th e results: 25.2% arts and humanities, 19.3% business, 7.1% education, 16.6% engineering and science, 7.8% professional, and 15.3% social science.3 (a) What percent plan to study fi elds other than those listed? (b) Make a graph that compares the percents of college freshmen planning to study various fi elds.

Girls excel Is it true that girls perform better than boys in the study of languages and so-called soft sciences? Here are several Advanced Placement subjects and the percent of examinations taken by female candidates in 2007: English Language/Composition, 63%; French Language, 70%; Spanish Language, 64%; and Psychology, 65%.4 (a) Explain clearly why we cannot use a pie chart to display these data, even if we know the percent of exams taken by girls for every subject. (b) Make a bar graph of the data. Order the bars from tallest to shortest; this will make comparisons easier. (c) Do these data answer the question about whether girls perform better in these subject areas? Why or why not?

Cell phones and driving Th e Harris Poll survey of Example 2.3 (page 39) also provided results about cell phone use and driving by age group. Here is a table that summarizes the percent of each age group who said they Always or Sometimes use cell phones while driving Age group Gen. Y Gen. X Baby boomers Matures 86% 79% 76% 48% (a) Would it be appropriate to use a pie chart to display these data? If so, do it. If not, explain why not. (b) Make a bar graph of the data. Describe what you see.

Lottery sales States sell lots of lottery tickets. Table 2.2 shows where the money comes from. Make a bar graph that shows the distribution of lottery sales by type of game. Is it also proper to make a pie chart of these data?

Gooooaaal! Th e number of goals scored by each team in the fi rst round of the California high school soccer playoff s is shown below. 5 0 1 0 7 2 1 0 4 0 3 0 2 0 3 1 5 0 3 0 1 0 1 0 2 0 3 1 (a) Make a dotplot of the data. (b) Describe the distribution of the variable number of goals scored. Be sure to discuss the overall pattern (shape, center, and spread) and any deviations from that pattern.

Poverty in the states, I Table 2.5 shows the percent of people living below the poverty line in the 26 states east of the Mississippi. (a) Make a stemplot of these data. (b) Describe the distribution of the variable percent living in poverty. Be sure to discuss the overall pattern (shape, center, and spread) and any deviations from that pattern.

Driving in town In Example 2.4, we examined data on highway gas mileages of model year 2009 midsize cars. Th e Minitab dotplot below shows the EPA estimates of city gas mileages for these same 24 car models. Describe the overall pattern of the distribution and any deviations from that pattern.

Fuel effi ciency Refer to the previous exercise. Th e Minitab dotplot below shows the diff erence (HighwayCity) in EPA mileage ratings for each of the 24 car models from Example 2.4. What does the graph tell us about fuel economy in the city versus on the highway for these car models? Be specifi c.

Where do the young live? Figure 2.6 is a stemplot of the percent of residents aged 25 to 34 in each of the 50 states. As in Figure 2.5 (page 45) for older residents, the stems are whole percents and the leaves are tenths of a percent. Th is time, each stem has been split in two, with values having leaves 0 through 4 placed on one stem and values ending in 5 through 9 placed on another stem. (a) Utah has the highest percent of residents aged 25 to 34. What is that percent? Why does Utah have an unusually high percent of residents in this age group? (b) Describe the shape, center, and spread of the distribution, ignoring Utah. (c) Is the distribution for young adults more or less spread out than the distribution in Figure 2.5 for older adults? Justify your answer.

Watch that caff eine! Th e U.S. Food and Drug Administration limits the amount of caff eine in a 12-ounce can of carbonated beverage to 72 milligrams. Th at translates to a maximum of 48 milligrams of caff eine per 8-ounce serving. Data on the caff eine content of popular soft drinks is provided in Table 2.6. How does the caff eine content of these drinks compare to the USFDAs limit? Table 2.6 Caffeine Content (in Milligrams) for an 8-Ounce Serving of Popular Soft Drinks (a) You could construct a dotplot of the caff eine content data, but a stemplot might be preferable. Explain why. (b) Construct a stemplot of the data using the fi rst digit as the stem and the second digit as the leaf. What problem do you see with this display? (c) Figure 2.7 shows a stemplot with split stems for the caff eine content data. Th is time, values having leaves 0 through 4 are placed on one stem, while values ending in 5 through 9 are placed on another stem. Describe the shape, center, and spread of the distribution. Figure 2.7 Stemplot showing the caff eine content (in milligrams per 8-ounce serving) of various soft drinks.

Minority students in engineering Figure 2.10 is a histogram of the number of minority students (black, Hispanic, Native American) who earned doctorate degrees in engineering from each of 115 universities over a 5-year period.7 Briefl y describe the shape, center, and spread of this distribution.

Lightning fl ashes Figure 2.11 comes from a study of lightning storms in Colorado.8 It shows the distribution of the hour of the day during which the fi rst lightning fl ash for that day occurred. Describe the shape, center, and spread of this distribution. Are there any outliers?

Poverty in the states, II Refer to Exercise 2.8 (page 46). Joe made the histogram shown below from the poverty data in Table 2.5. Write a sentence or two clearly explaining to Joe why his histogram is not legitimate.

Poverty in the states, III Refer to Exercise 2.8 (page 46). Make a histogram for the data in Table 2.5. Use seven classes of width 2, beginning with 79. If you made a stemplot of these data in Exercise 2.8, how does your histogram compare?

Yankee money Table 2.7 gives the salaries of the players on the New York Yankees baseball team for the 2008 season. (a) Make a histogram of these data. (b) Is the distribution of Yankees salaries roughly symmetrical, skewed to the left , or skewed to the right? Explain briefl y. (c) What is the spread of the distribution?

Activity 2.1C follow-up Use the CEREALS data from Activity 2.1C and the One Variable Statistical Calculator applet on the books Web site (www.whfreeman.com/sta2e) to investigate the calories, sugar, or fat content of the 77 brands of cereal. Make a histogram of the variable you chose. Write a brief report describing what you learned.

Feeling sleepy? Students in a college statistics class responded to a survey designed by their teacher. One of the survey questions was How much sleep did you get last night? Here are the data (in hours): 9 6 8 6 8 8 6 6.5 6 7 9 4 3 4 5 6 11 6 3 6 6 10 7 8 4.5 9 7 7 (a) Make a dotplot to display the data. (b) Describe the overall pattern of the distribution and any deviations from that pattern.

Bad habits According to the National Household Survey on Drug Abuse, 31.8% of adolescents aged 12 to 17 years used alcohol in 2007, 12.5% used marijuana, 1.5% used cocaine, and 15.7% used cigarettes. Explain why it is not correct to display these data in a pie chart.

Low birth weights Figure 2.12 (on the next page) shows the distribution of percent of low birth weights for the 26 states east of the Mississippi.10 Notice that the vertical scale in Figure 2.12(a) is the number of states in each class. In Figure 2.12(b), we have calculated and displayed the percent of states in each low-birth-weight class. (a) Describe the shape, center, and spread of the distribution. (b) When might it be preferable to use percents rather than counts on the vertical axis of a histogram? (c) Mississippi had the highest percent of low birth weight, 10.1. Why do you think this state has such a high percent of low-birth-weight infants?

Skewed left (a) Sketch a histogram for a distribution that is skewed to the left . (b) Suppose that you and your friends emptied your pockets of coins and recorded the year marked on each coin. Th e distribution of dates would be skewed to the left . Explain why. Exercises 2.23 to 2.26 refer to the following setting. CensusAtSchool is an international project that collects data about primary and secondary school students using surveys. As of early 2009, students in Australia, Canada, New Zealand, South Africa, and the United Kingdom have participated in the project. Data from CensusAtSchool surveys are available from the projects Web site, www.censusatschool.com. We used the Random Data Selector to choose a simple random sample of 50 Canadian students who completed the survey in 20072008. The data set CASCAN0708 can be found on the books Web site, www.whfreeman.com/sta2e.

Lets chat Th e bar graph on the left displays data on students responses to the question Which of these methods do you most oft en use to communicate with your friends? (a) Would it be appropriate to make a pie chart for these data? If so, do it. If not, explain why not. (b) Summarize what the bar graph tells you about students communication preferences.

Travel time Th e dotplot on the facing page displays data on students responses to the question How long does it usually take you to travel to school? (a) Make a well-labeled histogram of the data. (b) Describe the shape, center, and spread of the distribution. Are there any outliers?

Whos left-handed? Students were asked, Are you right-handed, lefthanded or ambidextrous? The responses of the 50 randomly selected Canadian students are shown below (R  right-handed; L  left-handed; A  ambidextrous). R R R R R R R R R R R L R R R R R R R R R R R R R R R A R R R R A R R L R R R R L A R R R R R R R R (a) Make an appropriate graph to display these data. (b) Over 10,000 Canadian high school students took the CensusAtSchool survey in 20072008. What percent of this population would you estimate is left -handed? Justify your answer

How tall are you? Here are the heights (in centimeters) of the 50 randomly selected Canadian students who participated in CensusAtSchool in 20072008. 166.5 170 178 163 150.5 169 173 169 171 166 190 183 178 161 171 170 191 168.5 178.5 173 175 160.5 166 164 163 174 160 174 182 167 166 170 170 181 171.5 160 178 157 165 187 168 157.5 145.5 156 182 168.5 177 162.5 160.5 185.5 Make a stemplot of these data. Describe the shape, center, and spread of the distribution. Are there any outliers?

Median income You read that the median income of U.S. households in 2007 was $50,233. Explain in plain words what the median income is.

Acing the fi rst test Here are the scores of Mrs. Liaos students on their fi rst statistics test: 93 93 87.5 91 94.5 72 96 95 93.5 93.5 73 82 45 88 80 86 85.5 87.5 81 78 86 89 92 91 98 85 82.5 88 94.5 43 (a) Find the median. Explain what this number means in this setting. (b) Find the quartiles and the IQR. Interpret the meaning of the IQR in this setting. (c) Are there any outliers? Justify your answer with appropriate calculations. (d) Make a boxplot of the test score data.

Phone calls, I After hearing about the text message study of Example 2.10, Mrs. Krebs asked the students in her statistics class how many phone calls they had made or received in the past 24 hours. Here are their responses: 3 0 12 10 8 4 2 7 10 11 6 7 0 35 12 3 10 2 7 9 15 5 14 15 6 (a) Find the median. Explain what this number means in this setting. (b) Find the quartiles and the IQR. Interpret the meaning of the IQR in this setting. (c) Determine whether there are any outliers. Show your work.

Phone calls, II Refer to the previous exercise. Make a boxplot of the phone call data from Mrs. Krebss class. How would you describe the distribution of the variable number of phone calls made or received in the past 24 hours?

Texting or calling, I After hearing about the text message study of Example 2.10, Mr. Williams collects data from each student in his math class on the number of cell phone texts and calls sent or received in the past 24 hours. Figure 2.14 is a boxplot of the difference (texts calls) in the number of text messages and calls for each student. (a) Estimate the fi ve-number summary for these data from the boxplot. (b) Interpret the value of Q1, M, and Q3 in this setting.

Texting or calling, II Refer to the previous exercise. (a) Do Mr. Williamss students seem to prefer texting or talking on the phone? Give appropriate evidence to support your answer. (b) Can we draw any conclusion about the preferences of all students in the school based on the data from Mr. Williamss math class? Why or why not?

Metabolism, I A persons metabolic rate is the rate at which the body consumes energy. Metabolic rate is important in studies of weight gain, dieting, and exercise. Here are the metabolic rates of seven men who took part in a study of dieting. (Th e units are calories per 24 hours. Th ese are the same calories used to describe the energy content of foods.) 1792 1666 1362 1614 1460 1867 1439 Use the formula to calculate the mean. Interpret this value.

Metabolism, II Refer to the previous exercise. (a) Use the method in Example 2.15 to calculate the deviation of each observation from the mean. Show that the sum of the deviations is 0. (b) Calculate the standard deviation. Show your work.

Mean income You read that the mean income of U.S. households in 2007 was $67,609. Recall from Exercise 2.27 (page 65) that the median U.S. household income in 2007 was $50,233. Explain why the mean household income is so much higher than the median household income.

Feeling sleepy? Th e fi rst four students to arrive for a fi rst-period statistics class were asked how much sleep (to the nearest hour) they got last night. Th eir responses were 7, 7, 9, and 9. (a) Use the formula to calculate the mean. Interpret this value. (b) Use the method in Example 2.15 to calculate the deviation of each observation from the mean. Th en compute the standard deviation. Explain what this value means.

A matchup Match the summary statistics with the histograms. Explain how you made your decision. (a) mean 6.6, median 6.8, standard deviation 1.3, variable . (b) mean 6.6, median 6.0, standard deviation 8.65, variable . (c) mean 6.6, median 3.75, standard deviation 7.4, variable .

Properties of the standard deviation (a) Juan says that, if the standard deviation of a list is zero, then all the numbers on the list are the same. Is Juan correct? Explain your answer. (b) Letishia alleges that, if the means and standard deviations of two diff erent lists of numbers are the same, then all of the numbers in the two lists are the same. Is Letishia correct? Explain your answer.

Music CDs How many music CDs do students own? Th e 24 members of a college statistics class provided data in response to this question.14 Figure 2.17 is a dotplot of the data. Which would better summarize the center and spread of the distribution: (i) the mean and standard deviation or (ii) the median and IQR? Justify your answer.

Domain names When it comes to Internet domain names, is shorter better? According to one ranking of Web sites in 2008, the top 8 sites (by number of hits) were yahoo.com, google.com, youtube.com, live.com, msn.com, myspace.com, wikipedia.org, and facebook.com. Th ese familiar sites certainly have short domain names. Figure 2.18 is a histogram of the domain name lengths for the 500 most popular Web sites. (a) Estimate the mean and median of the distribution. Explain your method clearly. (b) If you wanted to argue that shorter domain names were more popular, which measure of center would you choosethe mean or the median? Justify your answer.

Tall or short, I Mr. Walker measures the heights (in inches) of the students in one of his classes. He uses a computer to calculate the following numerical summaries: Mean Std. dev. Min. Q1 Med. Q3 Max. 69.188 3.20 61.5 67.75 69.5 71 74.5 Next, Mr. Walker has his entire class stand on their chairs, which are 18 inches off the ground. Th en he measures the distance from the top of each students head to the fl oor. (a) Find the mean and median of these measurements. Show your work. (b) Find the standard deviation and IQR of these measurements. Show your work.

Tall or short, II Refer to the previous exercise. Mr. Walker converts his students original heights from inches to feet. (a) Find the mean and median of the students heights in feet. Show your work. (b) Find the standard deviation and IQR of the students heights in feet. Show your work.

Cool car colors Table 2.8 gives information about the most popular colors of vehicles purchased in 2007. Make a bar graph that compares the color distributions for full size/intermediate cars and SUVs/trucks. Describe any similarities and diff erences between the two distributions.

Tuna from where? Does mercury content in canned tuna diff er by country of origin? Th e Fathom boxplots and summary chart that follow provide information to help you answer this question. Write a few sentences comparing the distributions of mercury concentration based on country of origin. Country Count x s Min. Q1 M Q3 Max. Costa Rica 23 0.281 0.243 0.079 0.16 0.23 0.32 1.3 Ecuador 18 0.754 0.367 0.3 0.45 0.68 0.98 1.5 Malaysia 2 0.33 0.057 0.29 0.29 0.33 0.37 0.37 Mexico 33 0.31 0.285 0.064 0.14 0.18 0.38 1.4 Phillipines 3 0.031 0.006 0.025 0.025 0.034 0.035 0.035 Th ailand 50 0.126 0.148 0.012 0.043 0.065 0.16 0.73 United States 35 0.268 0.242 0.023 0.052 0.2 0.4 0.99

Electoral votes, I To become president of the United States, a candidate does not have to receive a majority of the popular vote. Th e candidate does, however, have to win a majority of the 538 electoral votes that are cast in the Electoral College. Figure 2.19 is a stemplot of the number of electoral votes for each of the 50 states and the District of Columbia. (a) Find the fi ve-number summary for this distribution. (b) Are there any outliers? Justify your answer with a calculation. (c) Make a boxplot for these data

Electoral votes, II Refer to the previous exercise. Which measure of center and spread would you use to summarize the distribution in Figure 2.19: (i) the mean and standard deviation or (ii) the median and IQR? Justify your answer.

Which is easierAP Calculus AB or AP Statistics? Th e table below gives the distribution of grades earned by students taking the AP Calculus AB and AP Statistics exams in 2008.15 Grade No. of exams 5 4 3 2 1 AP Calculus AB 222,835 22.1% 21.2% 17.9% 15.2% 23.7% AP Statistics 108,284 12.9% 22.7% 23.7% 18.8% 21.8% (a) Make an appropriate graphical display to compare the grade distributions for AP Calculus AB and AP Statistics. (b) Write a few sentences comparing the two distributions of exam grades. Can we tell which exam is easier? Explain why or why not.

Mean or median? You are planning a party and want to know how many cans of soda to buy. A genie off ers to tell you either the mean number of cans guests will drink or the median number of cans. Which measure of center should you ask for? Why? To make your answer concrete, suppose that there will be 30 guests and the genie will tell you either x  5 cans or M  3 cans. How many cans should you have on hand?

Poverty in the eastern states Th e poverty rates for states east of the Mississippi have been divided into northern and southern states, according to the geographic divisions used by the Census Bureau. Figure 2.20 shows boxplots of the poverty rates for the states in each region. Write a few sentences comparing the distributions.

Phosphate levels Th e level of various substances in the blood infl uences our health. Here are measurements of the level of phosphate in the blood of a patient, in milligrams of phosphate per deciliter of blood, made on six consecutive visits to a clinic: 5.6 5.2 4.6 4.9 5.7 6.4 (a) Find the mean from its defi nition. Show your work. (b) Find the standard deviation from its defi nition. Show your work. (c) Now enter the data into your calculator and use it to obtain x and s. Do the results agree with your hand calculations?

Teacher raises, I A school system employs teachers at salaries between $18,000 and $40,000. Th e teachers union and the school board are negotiating the form of next years increase in the salary scale. (a) If every teacher is given a $1000 raise, what will this do to the mean salary? To the median salary? Explain your answers. (b) What would an across-the-board $1000 raise do to the extremes and quartiles of the salary distribution? To the standard deviation of teachers salaries? Explain your answers.

Teacher raises, II Refer to the previous exercise. If each teacher receives a 5% raise instead of a $1000 raise, the amount of the raise will vary from $900 to $2000, depending on the present salary. (a) What will this do to the mean salary? To the median salary? Explain your answers. (b) Will a 5% raise increase the IQR? Will it increase the standard deviation? Explain your answers.

Id die without my phone! In a July 2008 survey of over 2000 U.S. teenagers by Harris Interactive, 47% said that their social life would end or be worsened without their cell phone.18 One survey question asked the teens how important it is for their phone to have certain features. Figure 2.25 displays data on the percent who indicated that a particular feature is vital. Explain how the graph gives a misleading impression.

Th e cost of fresh oranges Figure 2.26 is a line graph of the average cost of fresh oranges each month from January 2000 to December 2008. Th ese data, from the Bureau of Labor Statistics monthly survey of retail prices, are index numbers rather than prices in dollars and cents. Th at is, they give each months price as a percent of the price in a base period (in this case, the years 1982 to 1984). So 250 means 250% of the base price. (a) Th e graph shows strong seasonal variation. How is this visible in the graph? Why would you expect the price of fresh oranges to show seasonal variation? (b) What is the overall trend in orange prices during this period, aft er we take account of the seasonal variation?

Support the court? In 2005, CNN reported the results of a survey about a Florida courts decision to remove the feeding tube from coma patient Terry Schiavo, eff ectively ending her life. Figure 2.27 (on the next page) shows a bar graph of the data that CNN initially posted on its Web site. (a) What visual impression does the graph give about support for the courts decision? (b) Make your own graph that displays the data in a less misleading way. (Note: When notifi ed about the misleading nature of their graph, CNN posted a corrected version.)

Lottery ticket sales, I Figure 2.28 is a line graph of the total lottery ticket sales (in millions of dollars) in the United States from 1980 to 2007. Whats wrong with this picture?

Lottery ticket sales, II Refer to the previous exercise. Draw a new line graph of the data displayed in Figure 2.28 that isnt deceptive. Describe what you see.

Getting to school Students in a high school statistics class were given data about the primary method of transportation to school for a group of 30 students. Th ey produced the pictograph shown on the facing page. (a) How is this graph misleading? (b) Make a graph of the data that is not misleading.

The rise in college education The line graph on the facing page shows the rise in the percent of women 25 years old and over who have at least a bachelors degree. Identify at least two features of this graph that make it confusing or misleading.

Greeks on campus Th e question-and-answer column of a college campus newspaper was asked what percent of the campus was Greek (that is, members of fraternities or sororities). Th e answer given was that the fi gures for the fall semester are approximately 13 percent for the girls and 1518 percent for the guys, which produces a Greek fi gure of approximately 2831 percent of the undergraduates.26 Discuss the campus newspapers arithmetic.

Oatmeal and cholesterol Does eating Quaker Oatmeal reduce cholesterol? An advertisement included the following graph as evidence that the answer is Yes. (a) How is this graph misleading? (b) Make a new graph that isnt misleading. What do you conclude about the eff ect of eating Quaker Oats on cholesterol reduction?

Deer in the suburbs Westchester County is a suburban area covering 438 square miles immediately north of New York City. A garden magazine claimed that the county is home to 800,000 deer.27 Do a calculation that shows this claim to be implausible

We can read, but can we count? Th e Census Bureau once gave a simple test of literacy in English to a random sample of 3400 people. Th e New York Times printed some of the questions under the headline 113% of Adults in U.S. Failed Th is Test.28 Why is the percent in the headline clearly wrong?

Online card games Figure 2.29 (on the next page) shows the number of people playing card games at the Yahoo Web site on a Sunday and on a Wednesday in the same week. (a) Explain whats wrong with this graph. (b) Make a more appropriate graph to display these data.

Poverty Th e number of Americans living below the offi cial poverty line increased from 32,476,000 to 37,276,000 in the 10 years between 1998 and 2007. What percent increase was this? You should not conclude from this that poverty grew more common in these years, however. Why not?

CHANCE News wiki Th e CHANCE Web site at Dartmouth College contains lots of interesting stuff (at least if you are interested in statistics). In particular, the CHANCE News wiki at http://chance.dartmouth.edu/chancewiki features articles about published statistical results in the media, including deceptive statistics. Go to the site and fi nd an example of one of the following: leaving out essential information, implausible numbers, or faulty arithmetic. Try looking in the Forsooth column of a recent issue.

Longevity of presidents Table 2.9 shows the ages at death of U.S. presidents. (a) Make a stemplot of these data. Did you decide to split the stems? (b) Now make a histogram. Describe the shape, center, and spread of the distribution. Are there any outliers? (c) Which plot is better at displaying this distribution: a stemplot or a histogram? Why?

Be creative! Make up a list of numbers of which only 10% are above the average (that is, above the mean). What percent of the numbers in your list fall above the median?

of the British Royal College of Physicians. It shows the number and percent of deaths among men aged 35 and over from the chief diseases related to smoking. One of the entries in the table is incorrect and an erratum slip was inserted to correct it. Which entry is wrong, and what is the correct value? Lung cancer Chronic bronchitis Coronary heart disease All causes Number 26,973 24,976 85,892 312,537 Percent 8.6% 8.0% 2.75% 100%

Who sells cars? Figure 2.31 is a pie chart of the percent of passenger car sales in a given year by various manufacturers. (a) Th e artist has tried to make the graph more interesting by using the wheel of a car for the pie. Is the graph still a correct display of the data? Explain your answer. (b) Make a bar graph of the data. What advantage does your new graph have over the pie chart in Figure 2.31?

We pay high interest Figure 2.32 shows a graph taken from an advertisement for an investment that promises to pay a higher interest rate than bank accounts and other competing investments. Is this graph a correct comparison of the four interest rates? Explain your answer.

State SAT scores Figure 2.33 (on the next page) is a histogram of the average scores on the mathematics part of the SAT exam for students in the 50 states and the District of Columbia.29 Th e distinctive overall shape of this distribution implies that a single measure of center such as the mean or the median is of little value in describing the distribution. Explain why.

Are you wired? In late 2006, the Pew Internet and American Life Project conducted a telephone survey of 935 adults and their children aged 12 to 17. One question they asked was Do you, personally, happen to have . . . a desktop computer? A cell phone? An iPod or other MP3 player? A laptop computer? A PDA like a Palm Pilot or Blackberry? Th e table below summarizes the responses. Desktop Cell phone iPod/MP3 Laptop PDA Parent and teen both own one 64% 60% 22% 18% 1% Parent owns one, teen doesnt 19% 29% 7% 19% 12% Teen owns one, parent doesnt 8% 3% 29% 7% 7% Neither parent nor teen owns one 9% 8% 42% 56% 80% Make a bar graph comparing teens and parents ownership of these devices.

Home run king In 1927, Babe Ruth broke Major League Baseballs single- season home run record by hitting 60 home runs. Th e Babes record stood until 1961, when Roger Maris hit 61 homers in a season. Almost 40 years later, Mark McGwire (70) and Sammy Sosa (68) excited baseball fans by smashing Mariss record in the same season. Barry Bonds captured the record in 2001 by hitting 73 home runs in a season. Below are data on the number of home runs hit by Bonds and McGwire each season during the prime of their careers. Who is the better home run hitter? Make comparative boxplots and provide numerical evidence to support your answer. Bonds 16 25 24 19 33 25 34 46 37 33 42 40 37 34 49 73 McGwire 49 32 33 39 22 42 39 52 58 70

Getting more sleep An experiment was carried out with 10 patients to investigate the eff ectiveness of a drug that was designed to increase sleep time. Th e data below show the number of additional hours of sleep gained by each subject aft er taking the drug.30 (A negative value indicates that the subject got less sleep aft er taking the drug.) Do these data provide suffi cient evidence to conclude that the drug was eff ective? Follow the four-step problem-solving process from Chapter 1 in answering this question. 1.9 0.8 1.1 0.1 0.1 4.4 5.5 1.6 4.6 3.4

Sleep: hours or minutes? Refer to the previous exercise. Suppose the sleep increase data are converted from hours to minutes. How will this aff ect the mean, median, standard deviation, and IQR? Explain.