Researchers have been studying the trend in British automobile sales over the past few decades only to realize the significant fluctuations in the market. If the increase in truck market share between the 1930s and 1950s had been maintained across the studied period and beyond, what would the market share of truck sales be in the 2010s? Percentage of each type 50 40 30 20 10 Automobiles Sold in Great Britain 0 Motorcycle Car Truck Bus 16% 26% 36% 46% 56% 66% 76% 1930s 1950s 1970s 1990s

The idea of a large, stable middle class (defined as those with annual household incomes in 2010 between $39, 000 and $118, 000 for a family of three) is central to America’s sense of itself. The following table gives the percentage of middle-income adults in the United States from 1971 through 2011: Year 1971 1981 1991 2001 2011 Percent 61 59 56 54 51 A mathematical model giving the percentage of middle-class adults in the United States for the period under consideration is given by f(t) = −2.5t = 61.2 (0 ≤ t ≤ 4) where t is measured in decades, with t = 0 corresponding to 1971. (a) Plot the data points, and sketch the graph of f the function on the same set of axes.(b) What is the rate of change of the percentage of middle-income adults in the United States over the period from 1971 to 2011? (c) Assuming that the trend continues, what will the percentage of middle-income adults in the United States be in 2021?

Table 9.3 Total cholesterol in 25 patients after taking new statin drug. .. Population mean is 200. Cholesterol levels 219 191 198 214 163 264 248 182 235 209 152 148 145 189 213 230 181 180 100 219 102 249 282 188 264 D. b. Describe the effects of the statin drug on your sample. Do you see any change in the level of cholesterol after taking the drug? c. What is your research question? What are the null and alternative hypotheses? Decide if you want to do a one-tailed or two-tailed test. d. What test? Perform it? What is your critical value? Sketch a normal distribution and draw the critical value or values of z. f. What is your conclusion?

An entrepreneur who owns and operates two businesses (A and B) would like to analyze their profitability. They would like your help in the analysis. They give you the annual net profit (in thousands of $) for each business from 2008-2020. Table 1: Annual Net Profits for Businesses A and B Business Year Profit Business Year Profit 2008 -50 2008 -10 2009 57 2009 30 2010 71 2010 27 2011 64 2011 22 2012 60 2012 21 2013 50 2013 20 A 2014 41 2014 24 2015 59 2015 24 2016 71 2016 32 2017 71 2017 36 2018 74 2018 37 019 81 20 40 2020 97 2020 49 a. Suppose you want to graph the distribution of profits. Explain why using only one stem- plot might not be optimal for the analysis. b. Describe the correct stemplot to use. Generate this stemplot. Explain your steps. What can you say about the distribution from this stemplot? c. When are stemplots useful? And why is that? d. Suppose that instead of having 26 observations you have 200 observations. What graph should you generate? e. What other type of…

kln 2.18 The report "Trends in Education 2010: Community Colleges" (www.collegeboard.com/trends) included the accompanying information on student debt for students graduating with an AA degree from a public community college in 2008. Debt Relative Frequency None 0.62 Less than $10,000 0.23 Between $10,000 and $20,000 0.10 More than $20,000 0.05 a. Use the given information to construct a bar chart. b. Comment on student debt for public community college graduates.