This is a simulation of the radioactive decay of 400 radioactive nuclei. You can choose from three different half lives. Note that the nuclei turn blue when they have decayed, and the smooth purple line on the graph shows the ideal case. An actual case can deviate a bit from the ideal case because of statistical fluctuations (which make more of a difference when the number of nuclei is small, as it is here). See if you can estimate the half life in the three cases shown here.
Simulation first posted on 4-24-2017. Written by Andrew Duffy