The table below gives the distribution of educational level for persons age 25 and over in the U.S. in 1960, 1970, and 1991. ("Educational level" means the number of years of schooling completed.) The class intervals include the left endpoint, but not the right; for example, from the second line of the table, in 1960 about 14% of the people had completed 5-8 years of schooling, 8 not included; in 1991, about 4% of the people were in this category. Draw a histogram for the 1991 data.

You can interpret "16 or more" as 16-17 years of schooling; not many people completed more than 16 years of school, especially in 1960 and 1970. Why does your histogram have spikes at 8, 12, and 16 years of schooling?

Educational level

(years of schooling)

1960 1970 1991 0-5 8

6 2

5-8 14 10 4

8-9 18 13 4

9-12 19 19 11 12-13 25 31 39 13-16 9

11 18 16 or more 8

11 21 Source: Statistical Abstract, 1988, Table 202; 1992, Table 220. P-968