thus, the probability of selling 8 bags after 3 days is .018+.02352+.018+.02352+.02352+.018 = .12456
My problem is, I need to get all the possible number of bags sold in 3 days with their probabilities of occurring. Is there a way that I can compute for that easily? The true situation is working with more than 5 possible number of bags in a day.
I dont think there is an elegant way to solve this, like I understand you are looking for, primarily since this is a random discrete distribution. One way in which I can think you could solve this easier is to compute the probability of selling LESS than 8 bags in more than 5 days, and substitute that from 1. There are much less cases in this scenario.