Pb-203 has a decay rate constant of 3.71 x 10^-6 / s. You have a 20.5 microgram sample of Pb-203 a) Find the number of nuclei in the sample of Pb-203. b) Find the "activity" (rate of decay) of the sample in units of nuclei/ s. c) Find the "activity" (rate of decay) of the sample in units of Curies (Ci.) (l Ci = 3.70 x 10^10 nuclei / s.)