The chloropleth map is a classed chloropleth map that shows the number of males per 100 females for a census for the year 2000.Classed chloropeth maps combine a real areal units into smaller groups that are divided into intervals using the process of equal steps , quantiles, natural breaks or minimum variance .The map employs six different data classes that use equal aerial units a graded color series to show intensity.
The image was taken from:http://http://my.ilstu.edu/~jrcarter/Geo204/Choro/map-AmFact-4eqint-orange-80pct.jpg