Assuming that each roll isn't weighted. Each class could have a different roll on slot, and each slot could have a different roll on specific item, for all we know it could be a bell curve of possibilities for thee total items, which would put the odds of xur rolling anything two deviations away at a really low probability, this making actual odds of what we're seeing significant. There simply isn't enough information to compute it, and if we went about trying to prove any hypothesis, especially only 8 or so weeks in, we would have to conclude that their is a probability roll for specific classes. RNG in a computer system is never truly random anyhow, and they probably coded a loot table to add artificial longevity for certain items. IE, warlock is 40/40/20 in hands/chest/helm, and chest is 10/40/40/10 for the chest options. It isn't rocket appliances, but we can't use traditional computational statistics to try and make any accurate statement regarding this. I've heard rumor that bungie hand picks items for xur, but I would have to see a bungie confirmation for that. Anyhow, this argument is fairly moot as the OP demonstrated he wasn't approaching this conundrum openly, and is instead using useless numbers to prove a useless point.