Question

Iodine-125 has a half-life of about 60 days.

Answer 1

We know that Iodine - 125 has a half life of 60 days.
300 : 60 = 5 . It means that it was halved 6 times.
Therefore: 500 mg * 0.5^5 =
= 500 mg * 0.5 * 0.5 * 0.5 * 0.5 * 0.5 =
= 500 mg * 0.03125 = 15.625 mg
Answer: 3. 15.625 mg.