Probability of an unstable atom becoming stable and not

[Einstein's Cat]

Is the probability of an unstable atom becoming stable known and vice verse; is the probability of an unstable atom not becoming stable known? In other words if there were a thousands unstable atoms, how many of these unstable particles would become stable? Thank you very much for your help!

 

[Vanadium 50]

Zero. If it's unstable, it's unstable.