Q 12-13-026JEE MainMedium
A radioactive isotope has a half-life of $5$ years. Find the percentage of the original sample that remains after $15$ years.
Numerical value type. Enter your answer.
Answer: 12.5
$15$ years is $3$ half-lives: $\left(\dfrac{1}{2}\right)^3 = \dfrac{1}{8} = 12.5\%$.
Solution by Sreeraj P, M.Sc Physics