72% of all Americans live in cities with population greater than 100,000 people. If 31 Americans are randomly selected, find the probability that a. Exactly 20 of them live in cities with population greater than 100,000 people. b. At most 24 of them live in cities with population greater than 100,000 people. c. At least 20 of them live in cities with population greater than 100,000 people. d. Between 20 and 27 (including 20 and 27) of them live in cities with population greater than 100,000 people..