WarframeAlchemyLab ES
Parry

Farming plan

Parry

Arsenal: Parry
Dropped by
Ancient Infested Common 38.72 %
Infested Corpus Common 38.72 %
Infested Grineer Common 38.72 %
Chance of getting it by number of runs
0% 25% 50% 75% 100% 2 3 5 6 8 2 runs · 50% 2 runs · 50% 5 runs · 90% 5 runs · 90%

Each run has a 38.72% chance. The curve is 1−(1−p)ⁿ: there is never a guarantee, only growing confidence.