Answer:
A half life is the amount of time it takes for half of a mass of a given radioactive element to decay to something else. 36 days is 4 1/2 life cycles, so by running 1/2*4 , we get how much of the original substance would be left. That would be 1/16 of the original substance left.
Explanation:
Of course, this is not always perfect, and can vary. In addition, if less than 16 atoms of the original substance are present, there is instead a 1/16∗a chance of at least one remaining.
