Chance of potential for crafting belts.

Well is not that difficult to calculate... if after crafting 1000 there are 226 belts whit potential...

1000=100%
226=22.6%

if i am correct, the chances are 22.6%?

Should be.

Check out binomial for a probability though.

.25, 1000, 226 go into the boxes -> about a 3.5% chance of this occurring if that's the true underlying probability. (you want cumulative P(X<226) to be as close to 50% as possible, really)



Another way of looking at it:
In 1000 trials, 203 were rare. (just about 20%)
23 were epic (near 2%)

I'd say it's plausible you have a 20% chance of rare, 2% chance of epic, 0.2% chance of unique...