One important method of dating fossil remains is to determine what portion of
the carbon content of a fossil is the radioactive isotope carbon-14. During life,
any organism exchanges carbon with its environment. Upon death this
circulation ceases, and the^14 C in the organism then decays at a rate proportional
to the amount present. The proportionality factor is 0.012% per year.
When did an animal die, if an archaeologist determines that only 25% of the
original amount of ^14 C is still present in its fossil remains?
SOLUTION:
The quantity Q of 14 C present at time t satisfies the equation