This question is a follow-up to this one.
I've been wondering how small that probability is. As we all know, "safe" sex, that is (correctly) using a condom and all that, isn't perfectly safe. So, in order to put this question into perspective, I'd like to know which one (safe sex or indirect insemination) has the greater chance to lead to impregnation. In other words, can you explain the probability of this scenario in terms a layman like me can understand?
Thanks in advance!