Carbon-14 is used to determine the time an organism was living. the amount of carbon-14 an organism has is constant with the atmosphere, but when an organism dies the carbon-14 decays at a half-life of 5,730 years. if an archeologist measured the amount of carbon-14 in an organism and it was 25% of the total amount of atmospheric c-14, what is the age of the organism? 1432.5 years 5,730 years 11,460 years 17,190 years