Please answer all sections.

4. [4 points] 80 pianists compete in a piano competition. (a) In the rst round, 20 of the 80 are selected to go on to the next round. How many different outcomes are there for the rst round? (b) In the second round, the judges select a rst, second, third, and fourth place winner of the competition from among the 20 pianists who advanced to the second round. How many outcomes are there for the second round of the competition