I'm trying to find the probability that someone will return a product they purchased given a certain amount of days that have passed since their initial purchase.
For example, assuming a normal distribution and that I have 60 samples, with a S.D. = 34 days and Mean = 55 days, how can I determine the probability that someone will return a product given that they have kept it for 20 days?
How would I formulate this problem? I can calculate the Z-Score but I'm not sure where to go from there - is there some sort of model or distribution that I should look into?