Carbon Dating In Exercise,you are given the ratio of carbon atoms in a fossil.Use the information to estimate age of the fossil.In living organic material,the ratio of radioactive carbon isotopes to the total number of carbon atoms is about 1 to1012.(see example 2 in second 10.1) when organic materials dies,its radioactive carbon isotopes begin to decay,with a half-life of about 5715 years. So, the ratio R of carbon isotopes to carbon-14 atoms is modeled by
R = 10^-12(1/2)^t/5715 ,
where t is the time (in year) and t = 0 represent the time when the organic material died.
R = 0.27 * 10 - 12