Answer:
62.5 mg
Step-by-step explanation:
Half-life of Iodine-125 is 60 days
It means the sample loses weight twice in every 60 days
Solution 1
This is a GP with first term of 1000 mg, common ratio of 1/2 and number of terms:
Last term is the remaining sample after 240 days:
--------------
Solution 2
- Day 0 = 1000 mg
- Day 60 = 1000 mg/2= 500 mg
- Day 120 = 500 mg/2= 250 mg
- Day 180 = 250 mg/2= 125 mg
- Day 240 = 125 mg/2= 62.5 mg
Answer is: 62.5 mg of Iodine-125 remains after 240 days
