SOLUTION: The amt of a pollutant, measured in parts per million, in pine lake can be by A(t)=14e-0.16t where t is the number of years since a program clean up. How long will it take for the

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: The amt of a pollutant, measured in parts per million, in pine lake can be by A(t)=14e-0.16t where t is the number of years since a program clean up. How long will it take for the       Log On


   

Question 319888: The amt of a pollutant, measured in parts per million, in pine lake can be by A(t)=14e-0.16t where t is the number of years since a program clean up. How long will it take for the pollutant in pine lake to reach 7 parts per million.
ANSWER: 12.52 YRS OR 4.33 YRS
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
A%28t%29+=+14%2Ae%5E%28-.16t%29
The amount of pollutant in ppm at the
end of the program is %28A%29t+=+7
7+=+14%2Ae%5E%28-.16t%29
Take the ln of both sides
ln%28.5%29+=+-.16t
-.6931+=+-.16t
t+=+.6931%2F.16
t+=+4.33 yrs