Wood from an ancient stump has a ratio of carbon-14 to carbon-12 that is one-eighth that of new wood. About how old is the stump? (Carbon-14's half-life is 5730 years.)
A) 17,190 years
B) 11,460 years
C) 5730 years
D) 2865 years

Question

Quizplus · Accepted Answer

The ratio of carbon-14 to carbon-12 in the ancient stump is one-eighth that of new wood, indicating that three half-lives of carbon-14 (5730 years each) have passed, because $ \frac{1}{2^3} = \frac{1}{8} $. Therefore, the stump is approximately 3 x 5730 = 17,190 years old.

Wood from an Ancient Stump Has a Ratio of Carbon-14