The half-life of a certain radioactive substance is 8 years. What is the yearly percentage decay rate for this substance?
A) 6.51%
B) 8.3%
C) 9.22%
D) 6.25%

Question

Quizplus · Accepted Answer

The yearly percentage decay rate can be found using the formula: 
r = (ln2 / half-life) * 100%
r = (ln2 / 8) * 100%
r ≈ 8.3% (rounded to the nearest tenth)
Therefore, the correct answer is B, 8.3%.

The Half-Life of a Certain Radioactive Substance Is 8 Years