Hello, one of my friends came over to get some help on a homework problem, and it went past over my head im pretty good with stats, just dont know how to approach this to help him out. So a radionuclides' activity (Cesium 137) is measured in the year of 1981, (no date just year), and its 60mCi, and its present activity is measured on 02/05/2016. so i calculated the present act to be 26.84mCi. however, how do i find totaI uncertainty in the activity. I was thinking may be it was (InitialA^2 + FinalA^2)^2? However, there does seem to be error in the decay time due to not having a date opposed to just a year. any help?