Radium-223 has a half-life of 11.0 days. How much of a 60.0 mg sample of Ra-223 is still active after 44.0 days?

The answer to your question is 3.75 mg

Explanation:

Data

Radium-223

half-life = 11 days

mass = 60 mg

total time = 44 days

Process

1. - Draw a chart to start the calculation

Mass Number of days Half-lives

60 mg 0 0

30 mg 11 1

15 mg 11 2

7.5 mg 11 3

3.75 mg 11 4

Total number of days 44

Mass active after 44 days = 3.75 mg