Calculating Age of Old Sample with Carbon 14 Dating

[Sublime74]

Homework Statement

The amount of 14C in an old, isolated sample of vegetation is 0.692 that expected from a present day sample with an equivalent carbon content. Calculate the age of the old sample in years.

Homework Equations

Im fairly sure you use the following equation to solve this...ln(N/Nsub0)=-.693t/tsub(1/2) ...I could be wrong, because every time I attempt to use it nothing happens haha.

The Attempt at a Solution

 

[glueball8]

Try N=No*(1/2)^t/T

No = original amount of radioactive material
N = amount of amount of radioactive material remaining after t
t = time intercal
T =half life