7.34 Stratified random samples. Cook County, Illinois, has the second-largest population of any county in the United States (after Los Angeles County, California). Cook County has 30 suburban townships and an additional 8 townships that are Bartington Hanover Norwood Park Riverside Berwyn Lemont Oak Park Schaumburg Bloom Leyden Orland Stickney Bremen Lyons Palatine Thornton Calumet Maine Palos Wheeling Cicero New Trier Proviso Worth Elk Grove Niles Rich Evanston Northfield River Forest The Chicago townships are Hyde Park Jefferson Lake Lake View North Chicago Rogers Park South Chicago West Chicago Because city and suburhan areas may differ, the fitst stage of a multistage sample chooses an SRS of 6 suburban townships and a separate SRS of 4 of the mote heavily populated Chicago townships. This is called a stratified random sample: divide the population into groups using iriformation available in advance, then take separate SRSs in each group. Use Table B or software to choose this sample. (If you use Table B, assign labels in al phabetical order and start at line 101 for the suburbs and at line 110 for Chicago.)