Radioactive materials are often used in biological studies. A radiation biologist studies the rate of decomposition of a certain substance and obtains the following data:
Time (days)
|
0
|
4.0
|
8.0
|
12.0
|
16.0
|
Mass (μg)
|
20.20
|
16.08
|
12.80
|
10.19
|
8.11
|
How many micrograms will remain after 28 days?