A wooden artifact is found to have a carbon-14 activity of 1…

A wooden artifact is found to have a carbon-14 activity of 11.0 disintegrations per second.  Given that the carbon-14 activity of an equal mass of freshly cut wood is 15.2 disintegrations per second, determine the age of the artifact in years.  The half-life of carbon-14 is 5717 years.