SOLUTION: soil from beneath the church was found to have lost 12% of its carbon-14. How old was the soil?

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Question 250313: soil from beneath the church was found to have lost 12% of its carbon-14. How old was the soil?
Answer by drk(1908) About Me  (Show Source):
You can put this solution on YOUR website!
THe general formula we need is:
A+=+P%2A%281%2F2%29%5E%28t%2Fhalf_life%29%29
I think 1/2 life of carbon is 5280 years. If not use the correct number and these steps.
Also we have lost 12% which means 88% is till there. So we have
88+=+100%2A%281%2F2%29%5E%28t%2F5280%29
divide by 100 to get
.88+=+%281%2F2%29%5E%28t%2F5280%29
log both sides to get
-.0555173+=+%28t%2F5280%29%2A%28-.30103%29
t+=+973.76 years