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I have been set this question, and I am finding it extremely difficult to begin. So much information is given, I don't know how to start to answer it. Also, some of the terms are confusing...

A living specimen in equilibrium with the atmosphere contains one atom of 14C (half-life = 5730 yr) for every 7.7×10^11 stable carbon atoms. An archeological sample of wood (cellulose, C12 H22 O11) contains 22.2 mg of carbon. When the sample is placed inside a shielded beta counter with 89.0% counting efficiency, 950 counts are accumulated in one week. Assuming that the cosmic-ray flux and the Earth's atmosphere have not changed appreciably since the sample was formed, find the age of the sample.

So could somebody point me in the right direction to start with?

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# Homework Help: Calculating the age of a radioactive source

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