Question 165540
you start with 100% (1.00)


after 4.2 million years, you have 50% (.50) or 1 * .5  or (.5)^1


after another 4.2 million years, you have 25% (.25) or 1 * .5 * .5  or (.5)^2


after N cycles (they're called half-lives) you have (.5)^N remaining


(.5)^N=.076 __ taking log __ N(log(.5))=log(.076) __ dividing by log(.5) __ N=(log(.076))/(log(.5))


using a calculator __ N=3.7 (approx)


so the age of the meteorite is N times 4.2 million or 15.5 million (approx)