You're playing a game in which the probability of winning each round is .20. On average, how many rounds do you have to play to first win?
A. 20
B. 5
C. 15
D. .5
E. 10
The expected number of rounds to win is equal to 1/probability of winning, which in this case is 1/.20 = 5 rounds.
Therefore, the answer is B. 5