# At the end of 12 days, 1/4 of an original sample of a radioactive element remains. What is the half life of the element?

A. 24 days

B. 3 days

C. 48 days

D. 6 days

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- skeptikLv 73 months agoFavorite Answer
If 1/4 remains, two half-lives have passed. The first took it from the full original sample to one-half. The second took it from one-half to one-fourth.

Which means that its half-life is half the amount of time that has passed.

So the answer is D. 6 days.

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- Anonymous3 months ago
None of the above.

If three quarters was used in 12 days - that's a quarter used every 4 days - so I would think it should be 8 days.

- skeptikLv 73 months agoReport
That's not how a half life works.

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- Anonymous3 months ago
If 1/4 remains, then 2 half lives have passed. 12 days / 2 half lives = 6 days/half life.

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