11. The population of the United States is aging, though less rapidly than in other developed countries. Figure 5.31 is a stemplot of the percentage of residents aged 65 and over in the 50 states, according to the 2010 Census. The stems are whole percentages and the leaves are tenths of a percentage. (The software JMP was used to create the stemplot. Notice that this software put the low stems at the bottom of the plot and the high stems at the top of the plot.)
11.
(a) 17.4%
(b) The shape is single-peaked and roughly symmetric; the center is near 13.5%; the percentages vary between 7.8% and 17.4%.