SOLUTION: 10. The half-life of radioactive potassium is 1.3 billion years. If 10 grams is present now, how much will be present in 100 years? In 1000 years? 12.A fossilized leaf contains

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Question 65624This question is from textbook
: 10. The half-life of radioactive potassium is 1.3 billion years. If 10 grams is present now, how much will be present in 100 years? In 1000 years?
12.A fossilized leaf contains 70% of its normal amount of carbon 14. How old is the fossil?
This question is from textbook

Answer by Nate(3500)   (Show Source): You can put this solution on YOUR website!
A = Pe^(rt)
P/2 = Pe^(1,300,000,000r)
1/2 = e^(1,300,000,000r)
ln(0.5) = 1,300,000,000r
ln(0.5)/1,300,000,000 = r
r is about -5.33e-10
A = 10e^(r*100)
and
A = 10e^(r*1000)
I do not have a calculator with "e" right now.
0.7P = Pe^(rt)
0.7 = e^(rt)
I need to know the rate ....

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