Final answer:
The half-life of the radioactive element is 4000 years.
Step-by-step explanation:
The half-life of a radioactive element is the time it takes for half of the sample to decay. In this case, if 50% of the element remains after 4000 years, it means that it has gone through one half-life. To find the length of the half-life, we can use the given information and calculate:
- After 4000 years, 50% of the element remains.
- After 8000 years (2 half-lives), 25% of the element remains.
- After 12000 years (3 half-lives), 12.5% of the element remains.
- And so on.
Since it takes 4000 years for the sample to go through one half-life, we can conclude that the half-life of the radioactive element is 4000 years.