The age of a bone was to be determined by 14C dating. 14C has a half-life of 5,730 years, and a Geiger counter shows that the 14C in living tissue gives 15.2 cpm g-1 of carbon. If the same Geiger counter shows that the 14C in a sample of the bone gives 3.8 cpm g-1 of carbon, how old is the bone?

Answer 1

k = 0.693/t_1/2

Then
ln(No/N) = kt
Use 15.2 for No
Use 3.8 for N
Substitute k fro above.
Solve for t.