Summary: sealed source of a certain radionuclide to determine its half life They measure the activity of the source in counts per minute every hour for three days Here is a graph of their results To find the half life they choose any value of the counts per minute say 4000 and read off the time here about 2 hours and then do the same for half the number The time taken for the
Image Dimensions: 764 x 544
Image originally found here.