An ore sample contains 4,000 milligrams of a radioactive material. it has a half life of 1 day. this means that each day, the amount of material is one half of what it was the day before. how much will be in the sample on the eighth day?

You can set up a simple equation based on the information in the question:



Where m is the final mass, m0 is the initial mass, and n is the number of half-lives that have passed. We're told in the question that m0=4000 and n=8. Subbing these numbers in and solve for m gives 15.625 mg.