The Census Bureau's Current Population Survey shows 28% of individuals, ages 25 and older, have completed four

Question:

The Census Bureau's Current Population Survey shows 28% of individuals, ages 25 and older, have completed four years of college (The New York Times Almanac, 2006). For a sample of 15 individuals, ages 25 and older, answer the following questions:
a. What is the probability four will have completed four years of college?
b. What is the probability three or more will have completed four years of college?