Question

The half life of Co-60 is 5.20 years. How many milligrams of a 1.00mg sample remains after 6.55 years

Answer 1

For cobalt-60, which has a half-life of 5.27 years, 50% remains after 5.27 years (one half-life), 25% remains after 10.54 years (two half-lives), 12.5% remains after 15.81 years (three half-lives), and so on.

Explanation:

You can figue out the rest.