Estimate the percentage of radioactive material that remains in a sample after 2 years if the half-life of the material is 211 days. Round to the nearest hundredth of a percent.
A)0.52%
B)35.29%
C)9.09%
D)14.45%
E)1.20%

Question

Quizplus · Accepted Answer

After 2 years (or 730 days), there will be 3.46 half-lives (730/211 ≈ 3.46). Therefore, the percentage of radioactive material remaining is approximately 50% raised to the third power (since each half-life reduces the amount by half): 50%³ ≈ 12.50% ≈ 9.09% (rounded to the nearest hundredth of a percent). Therefore, the answer is C.

Estimate the Percentage of Radioactive Material That Remains in a Sample