failures = 78 operatingHours = 4551360 FIT=(failures/operatingHours)*10^9  = 17137.735   MTTF=10^9/FIT  = 58350.769 numYears=3 desiredLife=numYears*365*24  = 26280 surviorRate=e^(-FIT*10^-9*desiredLife)  = 0.637