I had carried out an experiement to determine the half life of proactinium and had plotted the graphs for the decay counts. But now I must calculate from the graphs, to find out the half life. There are 2 graphs, one is corrected count rate against time and the other in Corrected count rate (log) against time. I have to use a gradient for one of them and I dont know which one?! And how do I work out the other one?! What method do I use?!