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Number1Ballar
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Homework Statement
The technique known as potassium-argon dating is used to date old lava flows. The potassium isotope 40K has a 1.28 billion year half-life and is naturally present at very low levels. 40K decays by beta emission into 40Ar. Argon is a gas, and there is no argon in flowing lava because the gas escapes. Once the lava solidifies, any argon produced in the decay of 40K is trapped inside and cannot escape. A geologist brings you a piece of solidified lava in which you find the 40Ar/40K ratio to be 0.12. What is the age of the rock?
Homework Equations
N=N0(1/2)t/t[1/2]
where N is the number of nuclei, N0 is the initial number of nuclei, t is time allowed to decay and t[1/2] is the half life.
The Attempt at a Solution
I actually do not know where to start with this one. I'm not sure how to apply the ratio given, and what variable I am even looking for, or if I'm even supposed to look at the relevant equation.
Could someone please point me in the right direction?
Thanks in advanced!