The half-life of the radium isotope Ra-226 is approximately 1,599 years. What percent of a given amount remains after 200 years? Round your answer to two decimal places.
A) 91.70 %
B) 5.92 %
C) 93.70 %
D) 6.25 %
E) 0.92 %

Question

The half-life of the radium isotope Ra-226 is approximately 1,599 years. What percent of a given amount remains after 200 years? Round your answer to two decimal places. ​
A) 91.70 %
B) 5.92 %
C) 93.70 %
D) 6.25 %
E) 0.92 %

Quizplus · Accepted Answer

The decay formula is N(t) = N0 * (1/2)^(t/half-life). For Ra-226, after 200 years, N(t)/N0 = (1/2)^(200/1599) ≈ 0.9170 or 91.70%.

The Half-Life of the Radium Isotope Ra-226 Is Approximately 1,599