The half life of carbon 14 is 5730 years. If a 1-gram sample of old carbon is 1/8 as radioactive as 1-gram of a current sample, then the age of the old sample is about
A) 11,500 years.
B) 46,000 years.
C) 716 years.
D) 17,200 years.
E) 22,900 years.

Question

Quizplus · Accepted Answer

The half-life of carbon-14 is 5730 years, meaning the amount of carbon-14 halves every 5730 years. If the old sample is 1/8 as radioactive as a current sample, it has gone through three half-lives (since 1/2^3 = 1/8). Therefore, the age of the old sample is 3 times the half-life of carbon-14: 3 * 5730 = 17,190 years, which is approximately 17,200 years.

The Half Life of Carbon 14 Is 5730 Years