# If a live log contains 200g of carbon-14, how old is buried long that contains 12.5g of carbon-14?

Jan 2, 2016

$22920$ years

#### Explanation:

Count how many half-lives have elapsed.

$200 \rightarrow 100 \textcolor{w h i t e}{s s s}$ (1)
$100 \rightarrow 50 \textcolor{w h i t e}{s s s}$ (2)
$50 \rightarrow 25 \textcolor{w h i t e}{s s s}$ (3)
$25 \rightarrow 12.5 \textcolor{w h i t e}{s s s}$ (4)

$4$ half-lives have occurred. The half-life of carbon-14 is $5730$ years.

$5730 \times 4 = 22920$