SUPPLEMENTARY EXERCISES for ... - WH Freeman

Section 2 5Month Height (cm) Month Height (cm) Month Height (cm)Jan. 79.80 May 80.10 Sept. 79.94Feb. 79.66 June 80.23 Oct. 79.80Mar. 79.91 July 80.07 Nov. 79.39Apr. 80.00 Aug. 79.79 Dec. 79.51(a) Make a time plot of the weight data. Describe any seasonal variation that appears in theplot. In particular, which months correspond to the highest weights? Which correspond to thelowest?(b) Repeat the analysis of (a) for the height data.(c) Describe the similarities and differences between the weight plot and the height plot.S1.16 In villages such as Kalama, the prevalence of illness may slow the growth of children. Inparticular, diarrhea is a serious problem and a major cause of death for small children. Thefollowing table gives the average percent of days ill with diarrhea per month for the childrenwhose weight and height information appears in the previous exercise:Month Percent Month Percent Month PercentJan. 2.54 May 8.42 Sept. 1.20Feb. 1.82 June 6.87 Oct. 2.51Mar. 2.28 July 4.51 Nov. 2.34Apr. 6.86 Aug. 3.42 Dec. 1.27(a) Make a time plot. Describe any seasonal variation that appears in the plot. Which monthshave the highest average percent of days ill with diarrhea? Which months have the lowest?(b) Egyptian physicians say there are two peaks in the frequency of diarrhea, a primary peakand a secondary, lower peak. Is there evidence in these data to support this claim?(c) Compare your plot with those of the previous exercise. Can you formulate any theoriesconcerning the relationship between diarrhea and the growth of these children? Note thatillness in one month may not have an effect on growth until subsequent months. On the otherhand, a child who is not growing well may be more susceptible to illness.Section 2S1.17 The mean and median salaries paid to major league baseball players in 1993 were $490,000and $1,160,000. Which of these numbers is the mean, and which is the median? Explain youranswer.S1.18 A college rowing coach tests the 10 members of the women’s varsity rowing team on aStanford Rowing Ergometer (a stationary rowing machine). The variable measured is revolutionsof the ergometer’s flywheel in a 1-minute session. The data are446 552 527 504 450 583 501 545 549 506(a) Make a stemplot of these data after rounding to two digits. Then find the mean and themedian of the original, unrounded ergometer scores. Explain the similarity or difference in thesetwo measures in terms of the symmetry or skewness of the distribution.