IMO going thru the MGF is not an efficient method in this case , provided that you already know the mean and the variance . What you laid out sounds perfectly reasonable . Are you sure that you didn ' t mistate the statement the probability that this Poisson r . v . equals 0 is . 3679 ? <| sep |> What if there ' s a third dude holding their sacks back though ? <| sep |> I think the biggest problem with desk jobs is that they can destroy your mobility if you let them . Shoulder , hand , hip , and leg flexibility really take a hit . I recommend doing some type of stretch routine in the bathroom every 90 minutes . Squat , rotate your shoulders , stretch your legs . Even a few minutes is better than nothing . And you will feel more refreshed when you sit down again .