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 = 0.22 * 10 - 12