Question

How old is a fossil that has radioactively decayed through 4 half-lives of carbon-14?

Answer 1

`"22,920"` years old.

Explanation:

Carbon-14 has a half life of 5730 years. This means it takes 5730 years for half of the carbon-14 atoms to decay to carbon-12 in a given sample (eg: 100 carbon-14, one half life = 50 carbon-14, 50 carbon-12).

`"4 half lives" = 5730 xx 4 = "22,920 years old"`

-Fish