CHAPTER 1 1 Section 1.1 Solutions 1.1 (a) The cases are the people who are asked the question. (b) The variable is whether each person supports the law or not. It is categorical. 1.2 (a) The cases are the 100 stocks. (b) The variable is the percentage change, which is a numerical quantity, for each of the stocks. It is quantitative. 1.3 (a) The cases are the teenagers in the sample. (b) The variable is the result (yes or no) indicating whether each teenager eats at least five servings a day of fruits and vegetables. It is categorical. 1.4 (a) The cases are the bunches of bananas in the sample. (b) The variable is the number of days until the bananas go bad. It is quantitative. 1.5 (a) The 10 beams that were tested. (b) The force at which each beam broke. It is quantitative. 1.6 (a) The cases are countries of the world. (b) The variable is whether or not the literacy rate is over 75%. It is categorical. 1.7 Since we expect the number of years smoking cigarettes to impact lung capacity, we think of the number of years smoking as the explanatory variable and the lung capacity as the response variable. 1.8 Since we expect the amount of fertilizer used to impact the yield (and not the other way around), we think of the amount of fertilizer as the explanatory variable and the yield of the crop as the response variable. 1.9 Ingesting more alcoholic drinks will cause the level of alcohol in the blood to increase, so the number of drinks is the explanatory variable and blood alcohol content is the response. 1.10 The world record time will continue to decrease as the years go by so we expect the year to impact marathon record time. We think of the year as the explanatory variable and the record time as the response variable. 1.11 (a) Year and HigherSAT are categorical. The other six variables are all quantitative, although Siblings might be classified as either categorical or quantitative. (b) There are many possible answers, such as “What proportion of the students are first year students?” or “What is the average weight of these students?” (c) There are many possible answers, such as “Do seniors seem to weigh more than first year students?” or “Do students with high Verbal SAT scores seem to also have high Math SAT scores?” 1.12 (a) In addition to the identification column, Country, there are 24 variables. We see that Developed is a categorical variable, while the other 23 variables are all quantitative. (b) There are many possible answers, such as “What is the average life expectancy for all countries of the world?” or “What proportion of countries are developed?”