A cloth fragment is found in an ancient tomb.It contains 78% of the carbon-14 (half-life is 5700 years) that it is assumed to have had initially.How old is the cloth?
A)15,900 years
B)16,400 years
C)18,900 years
D)15,800 years
E)none of these

Question

Quizplus · Accepted Answer

The correct answer is A because the cloth fragment contains 78% of the carbon-14 that it is assumed to have had initially, which means that it has lost 22% of its carbon-14. The half-life of carbon-14 is 5700 years, so the cloth fragment is 5700 * log(1/0.78) = 15,900 years old.

A Cloth Fragment Is Found in an Ancient Tomb