Take Home Exercise #2 Answers
This is an interval variable, so all univariate statistics apply.
Mode = 0 (29%):  The most common number of children among Americans is no children.
Median = 2:  About half of Americans have none or one child and about half have 2 or more children. 
Mean
x f xf
0 813 0
1 455 455
2 719 1438
3 449 1347
4 188 752
5 93 465
6 32 192
7 25 175
8 27 216
2801 5040
Mean = 5040/2801 =  1.7994
1.8 Children
Americans have on average 1.8 children. 
Range = 0 to 8:  Americans range from having 0 to 8 children.
Standard Deviation
x f xf x*x x*x*f
0 813 0 0 0
1 455 455 1 455
2 719 1438 4 2876
3 449 1347 9 4041
4 188 752 16 3008
5 93 465 25 2325
6 32 192 36 1152
7 25 175 49 1225
8 27 216 64 1728
2801 5040 16810
See board for formula
s = 1.66
There is not a great deal of variation among Americans on the number of children that they have. 
71% of Americans have 0-2 children.