# Living matter has a carbon-14 activity of about 16 counts/min per gram of carbon. What is the age of an artifact for of which the carbon-14 activity is 8 counts/min per gram carbon?

$\text{16 counts per minute x" (1/2) = "8 counts per minute x" (1/2) = 4 "counts per minute.}$
$\text{It takes two half-lives to have a decay rate of 4 counts per minute.}$
$\text{The half-live of carbon-14 is 5730 years. }$
$\text{5730 years x 2 = 11,460 years old. }$