Carbon-14 has a half-life of years. If a sample of carbon contains 200 carbon-14 atoms, how many carbon-14 atoms did it contain years ago?
Elizabeth wants to find out the half-life of a radioactive sample. She measures the activity of the sample over time, and her results are shown in the table. What is the half-life of the sample?
Argon-41 has a half-life of 110 minutes. If a sample of argon contains 2 400 atoms of argon-41, how many atoms of argon-41 are left after five hours and thirty minutes?