1. The problem statement, all variables and given/known data A jet engine manufacturer estimates that the chance of a “critical-item” failure within a jet engine’s afterburner module is approximately 1 in 220. What is the standard deviation of the number of launches, before a “critical-item” failure occurs within a jet engine’s afterburner module? 2. Relevant equations I would guess that you would use the standard deviation equation, but im not really understanding what to use when they give you "1 in 120" Please Help?