So we did this lab about how we are to measure the half life of the beta decay of indium 116 (the indium 116 is captured by indium 115 and undergoes beta decay to become tin 116. Since the Indium 116 I reused I understand that every time we use it, the indium 116 becomes a little bit more tin

Question

So we did this lab about how we are to measure the half life of the beta decay of indium 116  (the indium 116 is captured by indium 115 and undergoes  beta decay to become tin 116. Since the Indium 116 I reused  I understand that every time we use it, the indium 116 becomes a little bit more tin

Question:

What I don't understand is how to consider the effects of short lived and long lived contaminants (separately) and how it will change the values and effect the graph?