A radioisotope has a half-life of 2.5 hours. What percentage of a sample would be left after 12.5 hours?
To calculate the percentage of a sample that would be left after a certain number of half-lives, we use the formula:
Percentage left = (1/2)^(number of half-lives) * 100%
In this case, the half-life of the radioisotope is 2.5 hours.
To find out how many half-lives occur in 12.5 hours, we divide 12.5 by 2.5:
Number of half-lives = 12.5 hours / 2.5 hours = 5 half-lives
Now, we can calculate the percentage left:
Percentage left = (1/2)^(5) * 100%
= (1/32) * 100%
= 3.125%
Therefore, after 12.5 hours, approximately 3.125% of the sample would be left.