1% drop rates... a thought expriment.

[Grey_Cain]

No, that's not right.

At a 1% drop rate, you'd have to beat it 69 times before you have a more than 50% chance of getting it. (that's 1-POW(1.0 - 1%, 69) = .5001)
After 100 times, your probability goes up to 63%.

Well, then you have to divide the 63% probability by 8 for the number of people that are going to be lotting on it, so ~8%.

Now, I can speak from experience about an 8% chance. My fifth overmelded materia slots had that 8% chance, and it took usually between 12-15 failures before something stuck. My longest fail streak was 21. So if it's 8% after 100 runs, it means you can expect to finally get a mirror commonly after about 1200-1500 kills, or 2100 or more for the unlucky streaks.