A particular radioactive isotope has a half-life of 3.10 weeks. What fraction of the original sample is left after 86.8 days?

Question

Quizplus · Accepted Answer

The half-life of a radioactive isotope is the time it takes for half of the radioactive atoms in a sample to decay. After one half-life, half of the original sample is left. After two half-lives, half of the remaining sample is left, or one-fourth of the original sample is left. After three half-lives, half of the remaining sample is left, or one-eighth of the original sample is left. And so on.In this problem, the half-life of the radioactive isotope is 3.10 weeks. After 86.8 days, which is 12.4 weeks, the sample has gone through 12.4 weeks / 3.10 weeks/half-life = 4 half-lives. Therefore, one-sixteenth of the original sample is left.

A Particular Radioactive Isotope Has a Half-Life of 3