Question

A sample to be used for medical imaging is labeled with F-18, which has a half- life of 110 min. What percentage of the original activity in the sample remains after 300min?

Answer 1

Let the final activity be x

$\ln \frac{x}{100}= -\frac{0.693}{110}*300\\ \ln \frac{x}{100}= -1.89\\ \ln x - \ln 100 = -1.89\\ \ln x =2.715\\ x= 15.10 \%$