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MDCAT Physics QUESTION #4394
Question 1
After 3 half-lives, the remaining fraction of a radioactive sample is:
  • $\dfrac{1}{2}$
  • $\dfrac{1}{4}$
  • $\dfrac{1}{8}$✔️
  • $\dfrac{1}{16}$
Correct Answer Explanation
After each half-life, the remaining fraction is halved. After $n$ half-lives: remaining fraction $= \left(\dfrac{1}{2}\right)^n$. After 3 half-lives: $\left(\dfrac{1}{2}\right)^3 = \dfrac{1}{8}$.