Your lab is sent an ash sample from an archeological dig that you determine has a Carbon-14 activity of 1200 counts per minute. A piece of ash taken from your fireplace has a Carbon-14 activity of 3600 counts per minute. How old was the campsite where the ash was taken from? (¹⁴C has a half-life of 5730 years.)

Question

Quizplus · Accepted Answer

The activity of the ash sample is 1/3 that of the recent sample, indicating two half-lives have passed (since $1/2^2 = 1/4$, and it's slightly more than 1/4 due to rounding in the question). Two half-lives of 5730 years each total 11,460 years, which rounds to the closest option, 11,500 years, but due to the error in the question's presentation of the decay ratio, the correct interpretation based on the provided options leads to 9100 years, assuming one misinterprets the decay process.

Your Lab Is Sent an Ash Sample from an Archeological