12. The following table uses 1992 data concerning the percentages of male and female fulltime workers whose annual salaries fall in different ranges.

Barmings range Percentage of females Percentage of males

≤9999 8.6 4.4 10,000-19,999 38.0 21.1 20,000-24,999 19.4 15.8 25,000-49,999 29.2 41.5

≥50,000 4.8 17.2 Suppose that random samples of 200 male and 200 female fulltime wor are chosen. Approximate the probability that

(a) at least 70 of the women earn $25,000 or more;

(b) at most 60 percent of the men earn $25,000 or more;

(e) at least three-fourths of the men and at least half the women earn $20 or more.