The question is that the human body contains 0.2% potassium by weight and the natural abundance of 40K is 0.0118%. The half life of 40K is 1.28x10^9 years and I have to calculate the activity in an adult weighing 75 kg. What I tried was to find the decay constant by 0.693/1.12x10^13 hours = 6.18x10^-14. Then I took the mass and divided it by the 40K 14.11kg/40 * 6.02x10^23 = 2.12 x10^23. Then I tried Activity=lambda*N =6.18x10^-14*2.12x10^23=1.31x10^10. The answer is supposed to be 4.39x10^-6 and I don't know what I'm doing wrong if someone could help me that would be very much appreciated.(adsbygoogle = window.adsbygoogle || []).push({});

**Physics Forums - The Fusion of Science and Community**

# Calculating activity using half life

Know someone interested in this topic? Share a link to this question via email,
Google+,
Twitter, or
Facebook

Have something to add?

- Similar discussions for: Calculating activity using half life

Loading...

**Physics Forums - The Fusion of Science and Community**