CAPE Physics Unit 2 · 2012 · Paper 1 · Question Q44

A freshly made sample of radioactive material gives a count rate of 8000\text{ counts per minute}. After twenty days, it gives a count rate of 500\text{ counts per minute}. What is the half-life of the material?

1. (A)4\text{ days}
2. (B)5\text{ days}
3. (C)20\text{ days}
4. (D)80\text{ days}