Consider a primitive slot machine which, for each quarter inserted, rewards the user with $10 with the probability 1/50. What is the probability of leaving with more money than one started if 100 quarters are inserted? Use the exact binomial distribution.
This leads to two questions. First, why is the hint in my first post useful. You said he needs at least 3 winning pulls so that you would need to calculate the probalibty that he wins 3 times, 4 times, .... 50 times. That would take a very long time. Second, what is the binomial distribution and what does it tell you? How would you use it to calculate the probability that the player wins exactly once?