If the half-life of a radioactive substance is 800 years, what fraction of the original material is left after 3,200 years?

Question

Quizplus · Accepted Answer

After each half-life of 800 years, the amount of substance remaining is halved. After 3,200 years, which is 4 half-lives (3,200 / 800 = 4), the substance would be halved 4 times. Starting with 1 (or 100%), halving it once gives 1/2, twice gives 1/4, three times gives 1/8, and four times gives 1/16.

If the Half-Life of a Radioactive Substance Is 800 Years