1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution This is the question which I'm working on: When an animal dies the radioctive carbon content of its body has an activity of 12 counts per gram per minute. Some animal remains are found to have an activity of 3 counts per gram per minute. If the half life of radioactive carbon id 5000 years,how old are the animal remains. My solution: Decay rate reduced from 12counts/gram/min to 3counts/gram/min. Therefore it must have passed 2 half-lives. So two half-lives must be 5000 x 2 = 10 000. Is my method right?