Question

A radioactive element has a half-life of about 28 years and sometimes contaminates the soil. After 51 years, what percentage of a sample of the element would remain?

Answer 1

28%

Answer 2

H = Half Life
T = Elapsed Time
A= Beginning Amount
B = Ending Amount

\[n=T/H\]
\[B = A/2^{n}\]
\[B \approx28.3\]