Final answer:
The half-life of Luckycharmium is 120 days, so when 50% of the sample remains, it will have taken 120 days.
Step-by-step explanation:
The question asks about the time it takes for 50% of a Luckycharmium sample to remain. This is the same as the time it takes for half of the sample to decay. Since the half-life of Luckycharmium is given as 120 days, it means that it takes 120 days for half of the sample to decay. Therefore, when 50% of the sample remains, 120 days will have passed.