5. Carbon-14 can be used to determine how long ago an organism died. When an organism is alive, the amount of C-14 in its body remains constant. When that organism dies, the amount of C-14 declines according the to the following beta decay equation: C-14 => β- + N-14. If a sabre tooth tiger was determine to have died 19,700 years ago, what percent of its radioactivity at the time of death was measured in its carcass? T1/2 for C-14 is approximately 5730 years.