Looking for math help

Been trying to masterwork my ring (gotten good enough rolls on everything else so its my last item).

Legendary ring so 3 stats + 2 from tempering = 5

Getting the 1 masterworked stat I want on proc 1 is 1/5, proc 2 is 1/25 or 1 / (55) and 3 would be 1/125 or 1/ (55*5) right?

Can anyone tell me what my odds are for having failed proc 2 over 50 times now?