Three new associates have been hired to work at Dewey, Cheatham and Howe, a large law office. The rate of success for new associates at the firm is 80%. Assuming that the performance of each associate is independent of the performance of the others, draw a three-stage probability tree and use it to determine the probability that
a. Only one of the new associates will succeed.
b. At least two associates will succeed.
c. None of the associates will succeed.