Decay Constant= 1.2*10^-4years^-1
What is the decay contant?
Decay constant is used to determine the half-life of a radioactive element and comes from this expression:
A=Ao.e^(kt), where A=amount remaining after t time, Ao=initial amount, k=constant of decay(which is always a negative number). You can figure the k by using this simple formula: k=ln(1/2) / half-life of the radioactive element. Since you have the decay constant, we can easily figure out the half-life of the radioactive element in your example: ln(1/2) / (1.2*10^-4)=~5,776 years.
