SOLUTION: Wood deposits recovered from an archaeological site contain 36% of the C-14 they originally contained. How long ago did the tree from which the wood was obtained die? (Round your a

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Question 792092: Wood deposits recovered from an archaeological site contain 36% of the C-14 they originally contained. How long ago did the tree from which the wood was obtained die? (Round your answer to the nearest whole number.)
________yr

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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Wood deposits recovered from an archaeological site contain 36% of the C-14 they originally contained.
How long ago did the tree from which the wood was obtained die?
(Round your answer to the nearest whole number.)
:
The radio-active decay formula: A = Ao*2^(-t/h), Where:
A = resulting amt after t time
Ao = initial amt (t-0)
t = time in yrs
h = half-life of substance (carbon 14 half-life is 5730 yrs)
:
Let initial amt = 1, then resulting amt = .36
:
2%5E%28-t%2F5730%29 = .36
Using nat logs
-t%2F5730*ln(2) = ln(.36)
-t%2F5730 = ln%28.36%29%2Fln%282%29
-t%2F5730 = -1.47393
t = -5730 * -1.47393
t = 8,446 yrs ago