4.32 Poverty and life expectancy. Exercise 4.31 discusses a study of the relationship between poverty level and life expectancy of men in 2010 in 20 groups of U.S. counties. The researchers were also interested in the relationship between poverty level and life expectancy of women in 2010 in these 20 counties. Here are the data for both men and women in the 20 groups of counties: LIFEEXP2 Percentile rank Life expectancy of males Percentile rank 55 60 65 Life expectancy of males 76.5 76 76 5 10 15 20 25 79 79 78 77.5 77.5 77.5 70 75 80 85 77 76.5 75 75.5 30 35 40 45 50 77 76.5 77 77 90 95 100 74 74 73 Percentile rank Life expectancy of females 5 10 15 83 83 82.5 82.5 82.5 82.5 82 81.5 20 25 30 35 40 45 50 82 82 Percentile rank 55 60 65 70 75 80 85 90 95 100 Life expectancy of 81 81 81 82 81 80 80.5 79 79.5 79 females

(a) Make a scatterplot of the life expectancy versus poverty percentile rank, using separate symbols for men and women.

(b) What does your plot show about the pattern of life expectancy? What does it show about the effect of sex on life expectancy?