SOLUTION: An anthropologist finds bone that her instruments measure it as 0.556% of the amount of Carbon-14 the bones would have contained when the person was alive. How long ago did the pe

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Question 981757: An anthropologist finds bone that her instruments measure it as 0.556% of the amount of Carbon-14 the bones would have contained when the person was alive. How long ago did the person die?
The half life of carbon 14 is 5,730 years. Round your answer to the nearest thousand.
Ive been stuck on this problem for 3 days. I do not understand this at all.

Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
An anthropologist finds bone that her instruments measure it as 0.556% of the amount of Carbon-14 the bones would have contained when the person was alive. How long ago did the person die?
The half life of carbon 14 is 5,730 years. Round your answer to the nearest thousand.
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Every 5730 years, 1/2 of the C14 is gone.
C = C14 left
Co = amount at death
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At y years after death, C = Co*(1/2)^(y/5730)
C = Co*0.00556
Co*0.00556 = Co*(1/2)^(y/5730)
0.00556 = (1/2)^(y/5730)
ln(0.00556) = (y/5730)*ln(0.5)
y/5730 = ln(0.00556)/ln(0.5)
y = 5730*ln(0.00556)/ln(0.5)
y =~ 42921.7
y =~ 43000 years

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