This is a continuation of the last post. Let’s slightly modify the process: stop when the box becomes empty. And what is the expected number of steps for this process? The first ball This is trivial. Whichever other ball is chosen, we always put it back. So until the first ball is chosen (and dropped),… Continue reading Removing Gacha: II, an expectation problem
Tag: mathematics
Removing Gacha: I, a probability problem
The actual problem is here on atcoder. I’ll build a solution from the bottom up. So here we go. Let’s say we have N balls (numbered 1 to N) from a box, and we do the following: And by the time the process is stopped, what’s the probability that the N-th ball has been taken… Continue reading Removing Gacha: I, a probability problem