Your probability calculations are... non standard. Although you get the right answer, it's not correct to treat a discrete probability distribution like it's co

Your probability calculations are... non standard. Although you get the right answer, it's not correct to treat a discrete probability distribution like it's continuous. A more standard approach would be to calculate, for an appropriate time unit, the single time event probability and apply a geometric distribution. Edit: you're also seeming to mix up the time to event with the number of events in an hour. Did you actually use your derivation to get to your time estimates, or did you do a simulation?