Question 1006578: The function 900e^-0.0099^x models the amount in pounds of a particular radioactive material stored in a concrete vault, where x represents the number of years since the material was put in the vault. If 900 pounds of material was placed in the vault, how much time will need to pass for only 369 pounds to remain?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! The function 900e^-0.0099^x models the amount in pounds of a particular radioactive material stored in a concrete vault, where x represents the number of years since the material was put in the vault. If 900 pounds of material was placed in the vault, how much time will need to pass for only 369 pounds to remain?
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Solve:: 900e^(-0.0099x) = 369
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e^-0.0099x = 123/300
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-0.0099x = ln(123)-ln(300)
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-0.0099x = -0.8916
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x = 90 years
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Cheers,
Stan H.
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