Question

The half-life of carbon-14 is 5,730 years. Assuming you start with 100% of carbon-14, what is the expression for the percent, P(t), of carbon-14 that remains in an organism that is t years old and what is the percent of carbon-14 remaining (rounded to the nearest whole percent) in an organism estimated to be 20,000 years old?

Answer 1

The general expression would be:
$P(t) = (\frac{1}{2})^{ \frac{t}{5730} }$
In an organism that is 20,000 years old (t = 20000), we would expect:
$P(t) = (\frac{1}{2} )^( \frac{20000}{5730} ) = 0.08898$
This menas there would be around 8.898% of carbon-14 remaining in the organism.