Lesson: Calculating the Activity of a Radioactive Source

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?

A laboratory technician orders a sample of radioactive material. When it arrives, he measures its activity at 300 Bq. If the time between the sample being produced and it being delivered to the technician was equal to 2 half-lives, what was the activity of the sample when it was produced?

What is the remaining percent of the original radioactive atoms in a radioactive sample after 4 half-lives have passed?