Question

The half-life of a radioactive isotope is 3,100 years. Half of the original amount of the isotope is left. How many years have passed?

Answer 1

6,200 years have passed

Step-by-step explanation:

If half of the original amount of the isotope is left, then two half-lives have passed.

The half-life of the isotope is 3,100 years, so two half-lives is
2 * 3,100 = 6,200 years.

Thus, 6,200 years have passed.