Physics

Problem

A radioactive source registers

800

counts per minute at

t=0

. Nine minutes later the count rate is

200

counts per minute. Assuming exponential decay, which of the following is closest to the sample’s half-life? a)

6.5\,\text{min}

2.3\,\text{min}

4.5\,\text{min}

9\,\text{min}