In a radioactive sample, 40K19 nuclei either decay into stable 40Ca20 nuclei with decay constant 4.5 * 10^-10 per year or into stable 40Ar18 nuclei with decay constant 0.5 * 10^-10 per year. 40K19 nuclei either decay into stable 40Ca20 nuclei with decay constant 4.5 * 10^-10 per year or into stable 40Ar18 nuclei with [...]
