If the half-life of carbon-14 is about 5,730 years, then a fossil that has one-sixteenth the normal proportion of carbon-14 to carbon-12 should be about how many years old?
A) 1,400
B) 2,800
C) 11,200
D) 16,800
E) 22,900

Question

Quizplus · Accepted Answer

The fossil has 1/16 the normal proportion of carbon-14, which means it has gone through 4 half-lives (since 2^4 = 16). Multiplying the half-life of carbon-14 (5,730 years) by 4 gives 22,920 years, which rounds to option E, 22,900 years.

If the Half-Life of Carbon-14 Is About 5,730 Years, Then