In this prior installment, it was questioned whether things have probabilities. Here I will show the range of possible daily decay probabilities for the isotope which arguably has the least-stable decay rate: Beryllium-7.
The highest decay rate ever caused (using high pressure experiments) is in red, leading to a half-life of 50 days (normal is 53.2), and the lowest decay rate ever theorized (but not yet produced) is in blue, leading to a half-life of 57 days.
Half-lives below 50 days and above 57 days are beyond the realm of possibility (they are physically impossible).
Lamda (daily) decay rates for Be-7: 1.205% to 1.375%
Thought Experiment
If an alien gave you a sample of atoms, and only allowed you to count them, not to weigh them, and if that sample reduces by half in under 50 days, then the probability that it was beryllium-7 is 0%.
If there is still more than half left beyond 57 days, then the probability is also zero. Using the natural limits of the probability of decay, it is possible to become 100% certain.