Question

Half life of radioactive substance is 20 days. What fraction of sample will remain after 60 days?

• A. $\frac{1}{2}$
• B. $\frac{1}{4}$
• C. $\frac{1}{8}$
• D. $\frac{1}{16}$

Answer 1

Answer: (C)

$\frac{1}{8}$

Answer 2

$\frac{A}{A_{0}}$ = $\left( \frac{1}{2} \right)^{x}$ Here x = 3.