Personal Loot Question

[Saltywaffles]

I apologize in advance if this is well known and I am just being an idiot for not knowing about it or seeing the obvious. My question is, what exactly is the pool size that loot draws from for a boss in a dungeon? To clarify what I really mean here is a hypothetical, say a boss can drop shoulders, boots, a single weapon and a single trinket. Now with the way the loot works for a given spec the shoulders and boots, in this example, have like 5 variations each. So my question is, when loot drops does it grab from a pool of 12 items (5 boots, 5 shoulders, 1 weapon or 1 trinket)? OR does it pull from 4 items (shoulder, boots, weapon or trinket) and if it happens to select the shoulders or boots then it rolls a second time for variation?

Sorry if that was fairly confusing I tried to make it clear as possible. I just want to get an idea for what the chances are of getting one of the single items like a weapon from the loot. Trying to get an idea if it is 1 out of 4 or 1 out of 12 (using this example). Thanks in advance for any help I appreciate it.

[Relapses]

Random loot is random. It doesn't roll twice based off of the item.

[Saltywaffles]

I appreciate the response but the loot being random does not have much to do with my question. I want to know that if I am going for a particular item, say a weapon, does the table that I am having to "rng" against 1 out of 4 or 1 out of 12. Cause despite that being random or not the drastically changes the percentages of chance to get a particular item.