The radioactive decay of carbon-14 is first-order and the half-life is 5800 years. while a plant or animal is living, it has a constant proportion of carbon-14 (relative to carbon-12) in its composition. when the organism dies, the proportion of carbon-14 decreases as a result of radioactive decay and the age of the organism can be determined if the proportion of carbon14 in its remains is measured. if the proportion of carbon-14 in an ancient piece of wood is found to be one quarter that in living trees, how old is the sample?